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ELECTRICAL CURRENT
ELECTRICAL CURRENT
• Atoms are in everything and are made up of equal amounts of positive and negative charges.
Types of Electrical Current
• Alternating current moves the impulse back and forth
• 1 cycle/sec is called a HERTZ
• Household current is 60 Hz.
Alternating current
• Type of current that enters your home
• Economical in being transported from power plant to home….. Less energy loss to friction.
A Safety Fuse protects your house from too much electrical current
Direct current
• Electricity flows directly from the negative [cathode] to positive [anode] terminals
• Less electricity loss due to friction
• Used in electronics
• Supplied by batteries and generators
Direct Current
• Direct current can be compared to the flow of water
Comparing Different Batteries
What is the difference in a D cell and an AA cell?
Important electrical terms
• VOLTAGE
• CURRENT
• RESISTANCE
VOLTAGE
• Electrical potential energy per charge • Measured in volt or joules/ coulomb• Referred to as “potential difference”• When generated by battery or
magnetic force, it is called electromagnetic force.
Voltage
• The force-like quantity that moves a coulomb of electrons
• The greater the voltage, the greater the flow of electrical current for the
same resistance
Current=I
•Flow of electrons through a conductor
•Measured in Amperes [Amps]
•1 amp= 1 coulomb/sec
Resistance
RESISTANCE [Ω]
• Measured in OHMS or Ω• One ohm= one volt/one amp• Depends of the type of conductor [i.e.
gold has a very low resistance while tungsten has a very high resistance]
• Insulators have extremely high resistance
• An increase in temperature will increase the resistance
RESISTORS
Multi-functional Digital Meter
CURRENT ELECTRICITY
TERM SYMBOL UNIT SYMBOL
VOLTAGE V VOLT= JOULE/COULOMB
V
CURRENT I AMP= COULOMB/SEC
A
RESISTANCE R OHM= VOLT/AMP
Ω
Electrical Work
• Work = voltage X charge
•W=Vq
•Unit for work = joule
Electrical Power
• Power = current X volts
• VI=P
• Unit for power = watt
SERIES CIRCUIT
SERIES CIRCUIT
Series Circuit-current• The total current
in a series circuit is equal to the amount of current that passes through the greatest resistor or load
Series Circuit-voltage
• Total Voltage is equal to the sum of the individual voltages in the circuit.
1.5V
0.5V
0.5V
0.5V
SERIES CIRCUIT
RESISTANCE
The total resistance in this circuit is equal to the SUM of the resistance in each resistor.
V=10x6 = 60V
V= 5x6 = 30V
6 amps
CURRENT
FLOW HERE
15 amps
TOTAL RESISTANCE
PARALLEL CIRCUITS
• More than one connection at each resistor or load
Parallel Circuits-Current
• The total current in a parallel circuit is equal to the sum of the current through each resistor.
Parallel Circuit-Voltage
• In a parallel circuit, the voltage is equal through out the entire circuit.
Parallel Circuit-Resistance
• The total resistance in a parallel circuit is always less than the least resistor in the system
Rt<1
Parallel Circuits
How is “electricity generated” or
“electricity and magnetism”?
Current and Magnetism
• The magnetic field lines around a long wire which carries an electric current form concentric circles around the wire. The direction of the magnetic field is perpendicular to the wire and is in the direction the fingers of your right hand would curl if you wrapped them around the wire with your thumb in the direction of the current.
Current and magnetism
• The right-hand rule helps us keep our direction straight…..
Electromagnets vs. Permanent
These three factors all increase the strength of an electromagnet:
•Increasing the current flowing through the coil
• Increasing the number of coils
• Putting a core of a magnetic material inside the solenoid. The iron core becomes magnetized itself and makes the field stronger.
Current and Magnetism
• If a wire is moved through a magnetic field, an electrical current is produced.
• This is an example of a generator
• If a current carrying wire is in a magnetic field then a force is produced. This is an example of a motor.
The electric Motor
http://www.walter-fendt.de/ph11e/electricmotor.htm
Generating Electric Current requires a magnetic field and the movement of a metal wire through the field
An Electric MOTOR can be an Electric Generator if it is turned by a mechanical force.
Solar Panels convert SUNLIGHT into ELECTRICITY
The Future of Transportation