Physics 10th Electromagnetism Unit no

10th Physics (EM) - By Prof. Syed Arfat Haider – For www.notespk.com

Nauman Sadaf _This copy is provided for www.notespk.com_A Smart Website for Smart Notes Page 1

Physics 10th Electromagnetism Unit no.15 By which principle the direction of magnetic field is determined?

By the principle of right hand rule we can determine the direction of magnetic field:

“Grasp a wire with your right hand such that your thumb is pointed in the direction of current

then curling fingers of your hands will point in the direction of magnetic field”.

Write a short note on magnetic field of solenoid.

A coil of wire consisting of many loops is called a solenoid. The field from each loop in a

solenoid adds to the fields of the other loops and creates greater total field strength.

Electric current in solenoid of wire produces magnetic field which is similar to the

magnetic field of a permanent bar magnet .when this current carrying solenoid is

brought closer to a suspended bar magnet, one end of the solenoid repels the north

pole of bar magnet. Thus, the current carrying solenoid behaves like magnetic.

Define electromagnet and write the names of its poles.

The type of temporary magnet which is created when the current flows through coil is called

an electromagnet.

Names of poles: 1. North Pole 2.South pole.

How can we find the poles of current carrying solenoid?

We can find the poles of current carrying solenoid,

“If we grip the coil with our right hand by curling our fingers in the direction of the

conventional current, our thumb will indicate the north pole of the coil.”



State Lenz’s law.

The direction of an induced current in a circuit is always such that it opposes the cause that

produces it.

Write the Faraday’s law of electromagnetic induction.

The process of generating an induced current in a circuit by changing the number of magnetic

lines of force passing through it is called electromagnetic induction.

Faraday’s law: “The value of induced e.m.f in a circuit is directly proportional to the rate of

change of number of magnetic lines of force through it”.

A conductor wire generates a voltage while moving through a magnetic field and why?

When a conductor wire is moved through a magnetic field current is produced through it due

to electromagnetic induction which generates voltage.

What are magnetic field lines?

Magnetic field lines are used to visualize the magnitude and direction of magnetic field.

How can we increase the magnetic force?

1. By increasing the current in wire.

2. By increasing the strength of magnetic field.

Explain the flaming left hand rule.

Stretch the thumb, forefinger and middle finger of the left hand mutually perpendicular to

each other. If the first finger points in the direction of magnetic field the middle finger in

the direction of the current, then the thumb would indicate the direction of force acting

on the conductor.



Explain the working principle of D.C. motor.

D.C. motor consists of commutator, brushes and armature coil. The position of coil is changed

by changing the direction of current due to which coil rotates continuously and current

flows in a loop. This is the working principle of D.C. motor.

What is function of split ring in D.C. motor?

Split rings work as commutator in D.C. motor. They are arranged so that coil rotates due to

which commutator also rotates. When rotating coil comes in vertical position then split

rings changes their position and the direction of current through coil is changed As a

result, the direction of the force on each side of the coil is reversed, which allows coil to

rotate continuously in magnetic field.

How the direction of electric current is reversed in the Armature coil of D.C motor.

Split rings are arranged so that coil rotates due to which commutator also rotates. When

rotating coil comes in vertical position then split rings changes their position and the

direction of current through coil.

What is armature?

Coil of D.C. motor is made of many loops mounted on a shaft or axle is called armature.

Define the strength of magnetic field, or define magnetic flux.

The number of magnetic field lines passing through any surface is called magnetic flux.

Write condition for minimum and maximum flux.



Maximum flux: The number of lines of force is maximum when the surface is held

perpendicular to the magnetic lines of force.

Minimum flux: It will be minimum when surface is held parallel to the magnetic lines of force.

Write the name of two factor that effect on induced e.m.f.

1. Speed of relative motion of coil and the magnet.

2. Number of turns of coil.

What is difference between D.C motor and A.C generator?

D.C motor: A device that is used to convert electrical energy into mechanical energy.

A.C generator: A device that is used to convert mechanical energy into electrical energy.

What is working principle of A.C generator?

When a coil rotates in a magnetic field, the induced current in it continuously changes from

maximum to minimum value and from minimum to maximum value and so on. This is

basic principle on which an A.C generator works.

Define mutual induction and self-induction.

Mutual Induction: The phenomenon of production of induced current in one coil due to

change of current in a neighboring coil called mutual induction.

Self-Induction: The production of induced current in a coil by itself is called self-induction.

What is transformer, at which principle it is work.

“Transformer is an electrical device which is used to increase or decrease the value of an

alternating voltage”.



Principle of working: Transformer works on principle of mutual induction.

What is meant by primary and secondary coil?

Primary Coil: Transformer consists of two coils. First coil is called primary coil. Its number of

turns are denote by Np.

Secondary Coil: The other coil of transformer called secondary coil. Its number of turns are

denote by Ns

Write types of transformer.

Step up transformer: A transformer which increases the voltage is called step up transformer.

In this transformer Ns > Np

Step down transformer: A transformer which decreases the voltage is called step down

transformer. In this transformer Ns < Np

A step up transformer has turn ratios of 1:100. An alternating supply of 20V is connected

across the primary coil. What is secondary voltage?

Given Data:

Np= 1

Ns=100

Vp=20V

Required:

Vs=?

Solution:

Vs/Vp = Ns/Np

Vs= (Ns/Np) x Vp

Vs= (100/1) x 20

Vs= 100 x 20

Vs= 2000 V



Can transformer work on D.C.?

No, Transformer cannot work on D.C.

Reason:

Direct current (DC) has no time varying field because current is constant as well as there is no

relative motion between coil and core(magnetic circuit) of the transformer. So there is no

induced e.m.f in secondary coil of the transformer. As Vs=0 Transformer fails to transfer power

from primary to secondary.

What is relay?

A relay is an electrical switch that opens and closes under the control of another electrical

circuit. The relay is used to control a large current with the help of a small current.

Physics 10th Basic Electronics Unit no.16 Define electronics.

Electronics is the branch of physics in which we study the characteristics of electronics by using

different electronic devices.

Define thermionic emission?

Emission of electron from the hot metal surface is called thermionic emission.

Example: Tungsten filament

When the tungsten filament is heated it represents the thermionic emission.

Write two factors which can enhance thermionic emission?

i) Current and voltage

ii) Temperature

Explain deflection of electrons by the electric field?

Take two parallel plates and place them at some distance. When the beam of electrons passes

between these plates. It bends towards the positive plate.



Reason: Because positive charge on plates attracts the electronics and negative charges repel

the electron. Properties of attraction or repulsion are due to force, F=qE

When q is the charge on electron and E is the electric field between the plates. Deflection of

electrons from their actual path is directly proportional to the electric field.

Explain deflection of electrons by magnetic field?

When we apply the magnetic field on the electron’s beam by horse shoe magnet. Electron’s

beam deviate from its actual path. If we change the direction of horse shoe magnet the

mark of electron’s beam on fluorescent screen deflect to its opposite direction.

N S

When a magnet is brought near the screen of a television tube, picture on the screen is distorted. Why?

When a magnet is brought near the screen of a television tube, the beam of electrons is deflected and does not

reach to the screen on exact points so the screen is distorted.

What is the evidence that rays of some kind are passing straight through the tube?

The shadow cast by the cross at the Centre of the tube gives evidence that rays of some kind are passing

through the tube.

Give two reasons to support the evidence that cathode rays are negatively charged electrons.

1) When electric field is applied to cathode rays they are deflected toward positive plate which is the

evidence that cathode rays are negatively charged particles.

2) When magnetic field is applied to cathode rays they are deflected toward negative plate which is the

evidence that cathode rays are negatively charged particles.

What will happen if an opaque object is placed in the path of cathode rays?

A shadow of the body will form if an opaque object is placed in the path of cathode rays

Define cathode-Ray oscilloscope. And write the name of its parts.



An instrument which is used to display the magnitude of changing electric currents or

potentials is called cathode ray oscilloscope.

Parts of CRO: 1.Electron Gun. 2. Deflecting plates. 3. Fluorescent screen.

Write the use of CRO.

1. CRO is used for displaying wave forms

2. It is used for measuring voltages.

3. It is used for range finding.

4. It is used in echo-sounding.

5. It is used to display heart beats.

Write the role of deflecting plates in CRO.

When beam of electrons emits from the electron gun, it passes between the two parallel

plates. The potential difference between the plates deflect the beam in vertical plane.

Pair of parallel plates on screen deflect the electrons in Y-axis in vertical direction while

pair of horizontal plates on screen deflect the electrons in X-axis or horizontal direction.

For what purpose electron gun is used in CRO.

1. In CRO electron gun is used to accelerate the beam of electrons.

2. Electron gun consist of electron source that is electrically heated cathode and emit

electrons.

3. Grid: there is a grid (G) in the electron gun that controls the flow of electrons.

What is fluorescent screen?

The screen of CRO consist of a thin layer of phosphor that is also called fluorescent screen. It

glow when electrons hit with it.

Differentiate between Analogue and Digital electronics.

Analogue Electronics: The branch of electronics consisting of circuits which process analogue

quantities, is called analogue electronics.

Example: sound system of public talk, Radio, Television and Telephone etc.



Digital Electronics: The branch of electronics composed of circuits which are used to study

digital quantities is called Digital electronics.

Write uses of digital electronics.

1. Digital cameras 2.Digital T.V. 3. Smart ID card development.

What is benefit of smart ID card?

A single card can be a passport, national insurance card and driving license all in one. All

biometric would be held digitally in the tiny chip.

Differentiate between Analogue & Digital quantities.

Analogue quantities: The quantities whose values change in a continuous way or remain same

are called Analogue quantities.

Example: Change in Temperature during the 24 hours of the day.

Tem

p

Time

Digital quantities: The quantities whose values change in a discontinuous way are

called digital quantities.

Example: Computer operations are based on digits.

Inp

ut

0 1 2 3 4

1

Numbers

Differentiate between ADC and DAC.

ADC: ADC stands for analogue to digital converter.

circuit that converts the analogue signal into digital signal is called analogue to digital

converter. (ADC)

DAC: DAC stands for digital to analogue converter.



circuit that converts the digital signal into analogue signal is called digital to analogue

converter. (DAC).

Define digital and analogue signal.

Analogue signal: The signals that change in a continuous way are called Analogue signals.

Example: In alternating current voltage, value of voltage change in continuously

between maximum (+5v) and minimum (-5v) therefore, it is an analogue signal.

-5v

+5v

Digital signal: The signals having only two particular values are called digital signal.

Example: The square wave signal is a digital signal, maximum voltage is (+5v) and

minimum is 0V.

00 0

+

V

Define Boolean variables.

Boolean variables are those variables which can have only two values 0 and 1.

Define Boolean algebra and binary variables.

Boolean algebra: The algebra that is used to represent the logic operations with the help of

symbols called Boolean algebra. It was invented by George Boole. It is also called

Algebra of logics.

Binary Variables: The things that have only two possible states are called binary variables.

These are represented by binary variables 0 and 1.

What is logic gate? Name three universal logic gates.



Logic gate: Logic gate is a switching circuit having two possible situations. It is in the form of

high voltage (1) or low voltage (0) OR it may be in the form of ON or OFF.

Three universal logic gates are:

1. AND gate

2. OR gate

3. NOT gate.

What is meant by AND gate? Write its truth table and symbol.

AND Gate: The circuit that implements the AND operation is called AND Gate.

Symbol:

Truth Table:

What is OR Gate? Write its symbol and truth table.

OR Gate: The circuit that implements the OR operation, is called OR gate.

Symbol:

A B X=A.B

0 0 0

0 1 0

1 0 0

1 1 1



Truth table:

What is NOT gate? Write its symbol and truth table.

NOT gate: The gate that is used to implement the NOT operation is called NOT gate.

Symbol:

Truth table:

A 0 1

X=

1 0

The basic operation of NOT gate is called inversion or complementation .Why?

A 0 0 1 1

B 0 1 0 1

X=A+B 0 1 1 1



The basic operation of NOT gate is called inversion or complementation because it inverts the

input values.

Q.22.Define NAND gate.

NAND gate: when we apply the AND operation on NOT operation then we get NAND

operation.

Symbol:

Truth table:

Q.23.What is NOR operation? Make truth table.

NOR operation: When we apply OR operation on NOT operation then we get NOR

operation.

Symbol:

A

B

X=A+B

Truth table:

A 0 0 1 1

B 0 1 0 1

X=

1 1 1 0

A B X=A+B



What is safety alarm? Write shortly.

Safety alarm is used for the safety of house. Single NAND gate is used in safety alarm.

Parts: NAND gate, LDR, Push button switch, Alarm.

What is the function of LDR?

LDR is light detecting resistor, its resistance decreases when exposed to light while its

resistance increases in dark. It is used as automatic switch.

In digital electronics one byte is equal to how many bits?

In digital electronics one byte is equal to 8 bits.

0 0 1 1

0 1 0 1

1 0 0 0



Physics 10th Information and

communication technology

Unit no.17

What is difference between Data and Information?

Data: Data are facts and figures that are used by program to produce useful information. It

may be in form of text, graphic or figure that can be recorded.

Information: In computer terminology the processed data is called information. Computer

processes the data and converts into the useful information. This information is

transmitted to distance places in the form of sound, pictures and computerized data.

What is information technology and telecommunication?

Information Technology: The scientific method used to store information, to arrange it for

proper use and to communicate it to others is called information technology. (IT).

Telecommunication: The method that is used to communicate information to far off places

instantly is called telecommunication.

What is information and communication technology?

Scientific method and mean to store, process and transmit vast amount of information in

seconds with the help of electronic equipment is called information and communication

technology (ICT).

Write the components of computer based information system.

There are 5 components of CBIS:

1. Hardware 2. Software 3. Data 4. Procedure 5. People



What is function of the transmitter and receiver?

Function of Transmitter: The transmitter process the input signal and send it to

transmission channel.

Function of Receiver: Receiver takes the output signal from transmission channel and

deliver it to the transducer after processing it. The receiver may amplify the input signal

to compensate for transmission loss.

What is fax machine? How is it work?

Fax machine is a devise that transmit information from one place to another place. It work like

photo copy machine.

Working: A fax machine basically scans a page to convert its text and graphic into electronic

signals and transmit it to another fax machine through telephone line. The receiving

machine converts the signals and uses a printer to create the copy of message that was

sent.

What is difference between telephone and cellular phone?

Telephone: Wires are used for transmission in telephone.

Cellular phone: Radio technology is used for communication in cellular phone.

What is cell phone and photo phone?

Radio technology is applied in the mobile phone. It is the type of Radio having two way

communication .A cell phone carries a radio transmitter and a receiver inside it. It sends

and receives the message in form of radio wave.

Photo phone: Contrary to common telephone, user can see the pictures of each other

through photo phone.

What is BSs and MSC?

Cell phone network system consist of cells and base stations (BSC) and mobile switching center

(MSC).



What is optical fibre?

Optical fibre cable is a bundle of glass fibre with thickness of a human hair. In which the light

travels in the form of total internal reflection. The inner side of optical fibre called core

and the outer side is called cladding.

Write uses of microwaves.

1) Microwaves are used in mobile phones, RADAR and satellite transmission in space.

2) Microwaves are used in satellite communication.

Why use of radio waves is not effective in satellite communication?

Radio waves may diffract due to different layers of atmosphere as a result signals become

weak and they cannot be transmitted far apart so radio waves are not effective for

satellite communication.

NOTE: on the other hand microwaves cannot be diffracted so they are used in satellite

communication.

What is computer? Write the name of its parts.

Computer is an electronic computing machine used for adding, subtracting or multiplying.

Parts: CPU, key board and monitor are basic parts of computer.

Name 4 output devices of computer.

1. Monitor 2.Printer 3.Speaker. 4. External storage device.

What is CPU? Why it is called the brain of computer.

CPU is the abbreviation of central processing unit. It is a hardware that contain a tiny

rectangular chip called as microprocessor. CPU called brain of computer because this

part translates instructions and performs calculations.

Define operating system and give an example.

An operating system is software that manages your computer and the devices connected to it

e.g. Windows and Linux.

Write uses of computer.



1. In offices, computer are used for preparing letters, documents and reports.

2. In hotels, the computer is used for advance booking of rooms, preparing bills and

providing enquiry services.

3. In Railways, computer are used for rail reservation. Printing of tickets and preparing

the charts.

4. Doctors, used computer to diagnosing illness and treatment of diseases.

What is ATM?

An electronic machine used for transection of money from banks.

What is super computer?

The most powerful and swift computer which can send an information in one thousand billion

part of second is called super computer. It contain many processors.

What is the language of computer?

Computer uses data in form of binary language i.e. 0 and 1, this is called computer language.

What is difference between Hardware and Software?

Hardware: The term hard ware refers to the machinery. The parts of computer that we can

touch are called hardware.

Example: CPU, monitor, key board, mouse,

Software: The term software refers to computer programs. The parts of computer that we

cannot touch are called software.

Example: Operating system (OS) is software.

What is difference between RAM and ROM memory?

RAM memory: It is used computer as temporary memory. RAM vanishes when the computer is

switched off. It is the abbreviation of Random Access Memory.

ROM memory: It starts the computer. It is abbreviation of Read Only Memory.



What is difference between Primary and secondary memory.

Primary memory: 1.It is based on electronics consist of integrated circuit.

It is temporary memory.

Secondary memory: It consists of audio-video cassettes etc. this is permanent memory.

Write names of information storage devices?

Audio video cassettes, floppy disk, hard disk and flash drive etc. are information storage

devices.

How data is stored in audio cassettes?

Audio cassettes are based on magnetism. Audio cassettes consist of a tape of magnetic

material on which sound is recorded in a particular pattern of a magnetic field.

What is Hard Disk and Floppy Disk? Or what is difference between index hole and hard disk?

Hard Disk: A hard disk is a rigid, magnetically sensitive disk that spins rapidly and

continuously inside the computer chassis or in separate box connected to computer

housing. This type of hard disk is never removed by the user.

Floppy Disk: Floppies are inexpensive, convenient and reliable, but they lack the storage

capacity and drive speed for many large jobs.

Index Hole: The small hole in the floppy disk which shows track on it is called index hole.

What is compact disk (CDs)?

This is based on laser technology .it is a molded plastic disk on which digital data is stored in

the form of microscopic reflection and non-reflecting spots which are called pits and

lands respectively. Pits are the spiral tracks enclosed on the top surface of CD and lands

are the areas between pits.

What is flash drive?

It is an electronic device that consists of data storage ICs. A flash drive is a small storage device

that can be used to transport files form one computer to another. They are slightly

larger than a stick of gum, yet many of different devices can carry all your home work

for an entire year.



Define word processing.

Word processing is a use of computer through which we can write letters, articles, books or

prepare a report. Word processing is a computer program using this program we can

develop any document and see it on the screen after typing.

What is data management?

To collect all information regarding a subject for any purpose and to store them in the

computer in more than one inter linked files which may help when needed is called data

management.

Advantages: Educational institute, libraries, hospitals and industries store concerned

information by data management.

What is meant by global web?

Internet is basically a large computers network, which extends all across the globe. This

worldwide network of computers is called global web.

What is Internet? What are services of Internet?

Internet: when many computer networks of the world were connected together, with the

objective of communicating with each other, internet was formed. In other words we

can say that internet is a network of networking, which spreads all across the globe.

Services: Web browsing: this function allows user to view web pages.

E-mail allows people to send and receive text messages.

Write a short note on Email. Or write services of Email?

One of the most widely used application of internet is Electronic mail. Which provides very fast

delivery of message to any enabled site on the internet. Communication through E-mail

is more quick and reliable.

1. Fast communication: We can send messages anywhere in the world instantly.

2. Simple to use: After initial setup of E-mail account, it is easy to use.

3. Cast free service: If we have an internet access, then we can avail the E-mail service

free of cast.



4. More efficient: We can send our message to many friends or people only in one action.

What is web browsers? Write names of web browsers.

Web browsing is a type of internet. Web browsing help the users to view web pages.

What is piracy?

The illegal duplication of copyright material like books, papers and software etc. is called

piracy.

What is E-commerce?

E-commerce is the way of doing business on the web. We can order our favourite book or any

other items on line.

Physics 10th Atomic and Nuclear physics Unit no.18 What is atom & atomic nucleus?

Atom: Atom is derived from Greek language’s word Otomos which means Indivisible.

Atomic Nucleus: The central part of an atom is called atomic nucleus.

Ruther ford discovered it in 1911.

Define Atomic number, Neutron number and Mass number.

Atomic number: The number of protons present in the nucleus of an atom is called charge

number or atomic number. It is represented by Z.

Neutron number: The number of neutron present in the nucleus of an atom is called Neutron

number. It is represented by N.

Mass number: Sum of protons and neutrons present in the nucleus of an atom is called Mass

number. It is represented by A.

Why does protons are not separated in nucleus due to presence of repulsive force?



Due to presence of strong nuclear force protons are not separated even in the presence of

repulsive force because strong nuclear force binds nucleus.

Define isotopes and give example.

The atoms of the elements having same atomic number but different mass number are called

isotopes.

Example: There are three isotopes of Hydrogen.

1. Protium ( 2.Deuterium 3.Tritium

Differentiate between Natural and Artificial radioactivity.

Natural radioactivity: The spontaneous emission of radiations by unstable nuclei is called

natural radioactivity.

Artificial Radio-activity: The process in which by bombardment of electrons, protons, neutrons

or alpha-particles, we convert stable elements into un-stable element is called Artificial

Radio-activity.

What is meant by radioactive elements?

The elements which emit radiations are called radioactive elements e.g. Uranium, Radium etc.

What is meant by background radiation?

Radiations present in the atmosphere due to different radio-active substances are called

background radiations.

Example: Everywhere on the earth e.g. stones, soil and water releases background

radiation.

Define cosmic radiations and give example.

Earth and all living things on the Earth also receive radiations from space, these radiations are

called cosmic radiations.

Example: Radiations from the sun.

Define Nuclear Transmutation.



The spontaneous process in which a parent unstable nuclide changes into a more stable

daughter nuclide with emission of radiations is called nuclear transmutation.

Example: 226 222 4

88 86 2Ra Rn He Energy

Radium Radon α-particle

Define Alpha-decay. Write its general equation.

During alpha decay, Atomic number Z of parent nuclide reduces by 2 and its atomic mass A

decreases by 4.

General Equation: 4 4

2 2

A A

n ZX Y He Energy

Parent nuclide daughter nuclide α-particle

Define Beta-decay, give example and general equation.

During Beta decay, parent nuclide atomic number increases by 1, while there is no change in

atomic mass.



General Equation: 0

1 1

A A

n ZX Y e Energy

Parent nuclide daughter nuclide β-particle

Example: 14 14 0

6 7 1C N e Energy

Carbon Nitrogen β-particle

Explain gamma decay with an example.

Gamma rays are emitted along with alpha or beta rays.

General Equation:



60 60 0

27 27 0

:

A A

Z ZX X

Example

CO CO Energy

Cobalt cobalt γ-rays

Write properties of Alpha, Beta and Gamma radiations.

Properties of Alpha particles:

1. These particles are Helium nuclei released with a high speed.

2. Their range is not greater than a few centimeters in gas.

3. They have positive charge.

Properties of Beta particles:

1. These particles have high energy electrons.

2. Their speed is almost equal to the speed of light.

3. They have negative charge, equal to electron.

Properties of Gamma rays:

1. These are high energy light photons. They are electro-magnetic radiation with very

small wavelength and high frequency.

2. Their wavelength and energy varies.

3. They are neutral.

What is meant by Ionization and penetrating power?

Ionization: The phenomenon by which radiation split matter into positive and negative ions is

called ionization.

Note: These types of radiation α, β and can ionize the matter.

Alpha particle have (greater than all radiation’s types) ionizing power.

Penetrating power: Ability of radiations to penetrate a certain material is called penetrating

power.



Note: Gamma-rays have greatest penetrating power.

Define half-life and write half-life of 14

6C . Or Write Half-life of Hydrogen, Lead and Uranium.

The period/time during which half of the unstable radioactive disintegrate is called half-life of

the sample of radioactive element.

Half-life of C-14 is 5730 years, Hydrogen is 12.3 years, Lead is 10.6 hours and

Uranium is 4.5×109 years.

How much of a 1g sample of pure radioactive substance would be left undecayed after four

half-lives?

After four half-lives 1/16 g of radioactive material will be left undecayed.

How long are you likely to wait to watch any sample of radioactive atoms completely decay?

It will take unlimited time to decay completely.

Differentiate between stable and unstable nuclei.

Stable Nuclei: The nuclei that does not produce radiations naturally is called stable nuclei.

Atomic number of mostly stable nuclei is between1 to 82.

Unstable Nuclei: The nuclei that produce radiations naturally is called unstable nuclei.

Atomic number of unstable nuclei is greater than 82.

What are radio-isotopes .write their two uses.

Elements made by artificial method are called radio-active isotopes or radio isotopes.

Uses: Tracers, Medical treatment and carbon dating etc.

What are Tracers?

Radio-active tracers are chemical compound in which some amount/number of radio-isotope is

found.

Use: They are used to determine the type of chemical reaction of metabolism in the

bodies of animals, plants and humans.

They are used as a tracer in the field of medicine, agriculture and industries.



Explain medical treatment of Radio-isotopes.

Radio-isotopes are used in nuclear medicine for the treatment of different diseases.

Example: Radio-active cobalt-60 used for treatment of cancer-cell and tumors.

Explain carbon-dating.

Determination of the age of living and non-living bodies, animals and plants by comparing it

with radio-activity of C-14 .this method is called Carbon dating.

Define fission reaction.

If we bombard slow neutrons on the heavy nucleus of Uranium, the nucleus of Uranium

disperses in two small nuclei by absorbing slow speed neutrons. This reaction is called

nuclear fission reaction.

General equation: 1 236 236

0 92 92n U U X Y neutrons

Slow stable unstable daughter

Neutrons uranium nuclide

What is fission chain reaction and how it can be controlled?

Two to three neutrons release during the fission reaction of U-235. In which every neutron

reacts with further nuclei to produce further 2-3 neutrons. By which, the number of

neutrons increases and reaction speeds up, this process is called chain reaction.



Method of controlling: We can control chain reaction by nuclear reactors. The neutrons

produced during fission reaction are absorbed in the rods of Boron and Cadmium.

Define nuclear fusion reaction.

When two light nuclei combine to form a heavier nucleus, the process is called nuclear fusion.

Equation:



Equation: 2 3 4 1

1 1 2 0I H He n Energy

Deuterium tritium Helium

What is cause of energy in Sun?

Energy coming from sun or stars is the result of fusion of hydrogen nuclei into helium with

release of energy. Temperature at the centre of sun is nearly 20 million kelvin which

makes the fusion favourable. In the reaction four hydrogen nuclei difuse together to

form a helium nucleus along with 25.7 MeV of energy.

Explain the risks of radiation

1. Beta and Gamma radiation burns the skin therefore, skin becomes red and

wounded.

2. Radiation cause blindness.

3. They cause leukemia means blood cancer.



Explain the preventive measure from risks of radiations.

1. Hold the sources of radiation with tongs and forceps.

2. All radio-active sources must be kept in lead boxes.

3. Do not point the sources of radiation towards any person.

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