BASIC ELECTRIC QUANTITIES AND CIRCUITS · 2019-11-22 · 14. Two particles, X (charge 2Q) and Y...

PHYSICS ~ CAPE LEVEL HAMPTON SCHOOL

BASIC ELECTRIC QUANTITIES AND CIRCUITS (Electric Current, Resistance, Ohm’s Law and Joule’s Law)

Teacher: G. David Boswell Date: October 24, 2017 Time Span: 09:15 a.m. to 10:00 a.m. Duration: 45 Mins

STUDENT: ____________________ ____________________ GRADE: ______ SURNAME FIRSTNAME

1. A coulomb is the same as: (A) an ampere/second (B) an ampere·second2 (C) an ampere/meter2 (D) an ampere·second

2. A kiloampere·hour is a unit of (A) current (B) energy (C) power (D) charge

3. The magnitude of the charge on an electron is approximately:

(A) (B) (C) (D)

4. The total negative charge on the electrons in 1 mol of helium (atomic number 2, molar mass 4) is:

(A) (B) (C) (D)

5. A wire carries a steady current of 2 A. The charge that passes a cross section in 2 s is:

(A) (B) (C) (D)

General Instructions: • Closed Book, Open Minds! Please attempt all questions and work neatly. • Please SHADE your response to the MCQs on the ANSWER SHEET PROVIDED • Mark scheme [ Correct (1 mark); Incorrect (0 mark); No Response (−1 mark) ]

1023C10−23C10−19C1019C

1.9 ×108C2.4 ×107C4.8 ×107C9.6 ×108C

2.3×10−19C6.4 ×10−19C2C4C

G. David Boswell | © BÖ§ZïK Inc.™ Hampton School, Jamaica Page of 1 6

6. A wire contains a steady current of 2 A. The number of electrons that pass a cross section in 2s is:

(A) (B) (C) (D)

7. The charge on a glass rod that has been rubbed with silk is called positive:

(A) by arbitrary convention (B) because like charges repel (C) because glass is an insulator (D) so that the proton charge will be positive

8. To make an uncharged object have a negative charge we must:

(A) add some atoms (B) remove some atoms (C) remove some electrons (D) add some electrons

9. To make an uncharged object have a positive charge we must:

(A) add some neutrons (B) remove some neutrons (C) remove some electrons (D) add some electrons

10. 11. An electrical insulator is a material: (A) containing no electrons

(B) through which electrons do not flow easily (C) that has more electrons than protons on its surface (D) cannot be a pure chemical element

11. A conductor is distinguished from an insulator with the same number of atoms by the number of: (A) nearly free atoms (B) molecules

(C) protons (D) electrons

12. A small object has charge . Charge is removed from it and placed on a second small object. The two objects are placed 1 m apart. For the force that each object exerts on the other to be a maximum. should be:

(A) (B)

(C)

(D)

13. Two small charged objects attract each other with a force F when separated by a distance . If the charge on each object is reduced to one-fourth of its original value and the distance between them is reduced to the force becomes:

(A)

(B)

(C)

(D)

2.5 ×1018

1.3×1019

2.5 ×1019

6.3×1018

Q q

q2QQQ2Q4

d

d / 2F16F8F4F2


14. Two particles, X (charge 2Q) and Y (charge Q), are 4m apart. The force of X on Y has:

(A) twice the magnitude of the force of Y on X (B) four times the magnitude of the force of Y on X (C) one-fourth the magnitude of the force of Y on X (D) the same magnitude as the force of Y on X

15. The units of 1/4π0 are: (A) (B) (C) (D)

16. A car battery is rated at 80 A·h. An ampere-hour is a unit of:

(A) power (B) energy (C) charge (D) current

17. Current has units: (A) kilowatt·hour (B) coulomb/second (C) volt (D) coulomb

18. Terminal p.d. has units: (A) kilowatt·hour (B) coulomb (C) volt (D) ampere

19. Atomic charge has units: (A) kilowatt·hour (B) coulomb (C) volt (D) ampere

20. The units of resistivity are: (A) ohm·meter (B) ohm (C) ohm·meter2 (D) ohm/meter

21. The rate at which electrical energy is used may be measured in:

(A) joule·second (B) watt (C) watt·second (D) watt/second

22. Energy may be measured in: (A) joule·second (B) kilowatt (C) watt·second (D) watt/second

23. Which one of the following quantities is correctly matched to its units?

(A) Power, (B) Energy, (C) Potential difference, (D) Resistance,

24. Current is a measure of: (A) force that moves a charge past a point (B) energy used to move a charge past a point (C) amount of charge that moves pass a point in unit time (D) speed with which a charge moves past a point

N 2 ⋅C 2

N ⋅m2 ⋅C−2

N ⋅m ⋅CN ⋅m2 ⋅C 2

kW ⋅hkW

J ⋅C−1

V ⋅C−1


25. A 60-watt light bulb carries a current of 0.5 A. The total charge passing through it in 1 hour is:

(A) (B) (C) (D)

26. A 10-ohm resistor carries a constant current. If 1200 C of charge flow through it in 4 minutes what is the value of the current?

(A) (B) (C) (D)

27. Conduction electrons move to the right in a certain wire. This indicates that:

(A) the electric field points to the right (B) the electric field points to the left (C) the electric field points to the upwards (D) the electric field points to the downwards

28. Two wires made of different materials have the same uniform current density. They carry the same current only if:

(A) their lengths are the same (B) both their lengths and cross-sectional areas are the same (C) the potential differences across them are the same (D) their cross-sectional areas are the same

29. A wire with a length of 150 m and a radius of 0.15 mm carries a current with a uniform current density of 2.8 × 107 A/m2. The current is:

(A) (B) (C) (D)

30. In a conductor carrying a current we expect the electron drift speed to be:

(A) much less than the average electron speed (B) about the same as the average electron speed (C) less than the average electron speed at high temperature and greater than the average electron speed at low temperature (D) much greater than the average electron speed

31. The current is zero in a conductor when no potential difference is applied because:

(A) the electrons are not moving (B) the electrons are not moving fast enough (C) for every electron with a given velocity there is another with a velocity of equal magnitude and opposite direction (D) otherwise Ohm’s law would not be valid

32. Copper contains 8.4×1028 free electrons/m3. A copper wire of cross-sectional area 7.4×10−7 m2 carries a current of 1 A. The electron drift speed is approximately:

(A) (B) (C) (D)

1800C2400C3000C3600C

3.0A5.0A11A15A

0.63A2.0A400A5.9A

3×108ms−1

103ms−1

10−23ms−1

10−4ms−1


33. Five cylindrical wires are made of the same material. Their lengths and radii are

wire 1: length , radius wire 2: length /4, radius /2 wire 3: length /2, radius /2 wire 4: length , radius /2 wire 5: length 5 , radius 2 Rank the wires according to their resistances, least to greatest. (A) 1, 2, 3, 4, 5 (B) 5, 4, 3, 2, 1 (C) 1 and 2 tie, then 5, 3, 4 (D) 1, 3, 4, 2, 5

34. Of the following, the copper conductor that has the least resistance is:

(A) thin, long and hot (B) thick, short and cool (C) thin, short and cool (D) thin, short and hot

35. A cylindrical copper rod has resistance R. It is reformed to twice its original length with no change of volume. Its new resistance is:

(A) (B) (C) (D)

36. The resistance of a rod does NOT depend on: (A) its temperature (B) its material (C) its length (D) the shape of its (fixed) cross-sectional area

37. A certain wire has resistance R. Another wire, of the same material, has half the length and half the diameter of the first wire. The resistance of the second wire is:

(A) (B) (C) (D)

38. A nichrome wire is 1 m long and 1 × 10−6 m2 in cross-sectional area. When connected to a potential difference of 2 V, a current of 4 A exists in the wire. The resistivity of this nichrome is:

(A) (B) (C) (D)

39. Which of the following graphs best represents the current-voltage relationship of an incandescent light bulb?

l rl rl rl rl r

0.5R2R4R8R

0.5R0.25R2R4R

2 ×10−7 Ω⋅m4 ×10−7 Ω⋅m5 ×10−7 Ω⋅m8 ×10−7 Ω⋅m

(A) (B)

(C) (D)

31. Which of the following graphs best represents the current-voltage relationship of an incandes-cent light bulb?

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ans: A

32. Which of the following graphs best represents the current-voltage relationship for a device thatobeys Ohm’s law?

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ans: B

33. Two wires are made of the same material and have the same length but different radii. Theyare joined end-to-end and a potential difference is maintained across the combination. Of thefollowing the quantity that is the same for both wires is:

A. potential differenceB. currentC. current densityD. electric fieldE. conduction electron drift speed

ans: B

382 Chapter 26: CURRENT AND RESISTANCE

www.allonlinefree.com


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ans: A


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ans: B



ans: B




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ans: A


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ans: B




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ans: A


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ans: B



ans: B




40. It is better to send 10,000 kW of electric power long distances at 10, 000 V rather than at 220 V because:

(A) more current is transmitted at high voltages (B) the insulation is more effective at high voltages (C) the drop along the wires is greater at high voltage (D) there is less heating in the transmission wires

41. A student kept her 60-watt, 120-volt study lamp turned on from 2:00 PM until 2:00 AM. How many coulombs of charge went through it?

(A) 3,600 (B) 7,200 (C) 18,000 (D) 21,600

42. A certain resistor dissipates 0.5 W when connected to a 3 V potential difference. When connected to a 1 V potential difference, this resistor will dissipate:

(A) (B) (C) (D)

43. Suppose the electric company charges 10 cents per kW·h. How much does it cost to use a 125 W lamp 4 hours a day for 30 days?

(A) (B) (C) (D)

44. A certain x-ray tube requires a current of 7 mA at a voltage of 80 kV. The rate of energy dissipation (in watts) is:

(A) 560 (B) 5600 (C) 26 (D) 87.5

45. An ordinary light bulb is marked “60 W, 120 V”. Its resistance is:

(A) (B) (C) (D)

BONUS! Shade your response below …

46. For an ohmic substance the resistivity is the proportionality constant for:

(A) current density and potential difference (B) current and electric field (C) current and potential difference (D) current density and electric field

- ENFIN -

i2R

500 mW56 mW167 mW1.5 W

$1.20$1.80$1.50$7.20

60 Ω120 Ω180 Ω240 Ω


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BASIC ELECTRIC QUANTITIES AND CIRCUITS · 2019-11-22 · 14. Two particles, X (charge 2Q) and Y...

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