Free Printable Current electricity Revision 12 C

1.

What happens to the brightness of the light bulbs in a series circuit when you add more lights.

a)

Each bulb gets dimmer

b)

Each bulb remains the same

c)

Half of the bulbs get dimmer

d)

Each bulb gets brighter

2.

If the voltage is increased and the resistance stays the same, current will ____.

a)

Increase

b)

Decrease

c)

Stay the same

d)

Not enough info

3.

If the voltage stays the same and resistance is increased, current will ________.

a)

Increase

b)

Decrease

c)

Stay the same

d)

Not enough info

4.

Find total resistance
total current
and the voltage through resistor 3.

a)

60 Ohms, 0.4 A, 8 V

b)

60 Ohms, 2.5 A, 4 V

c)

90 Ohms, 2.5 A, 24 V

d)

60 Ohms, 0.4 A, 24 V

5.

What is the power of a 3V light bulb with 20 A running through it?

a)

0.15W

b)

6W

c)

60W

d)

6.67W

6.

Two resistors are connected to a source of voltage as shown in the diagram below. At which position should an ammeter be placed to measure the current passing only through resistor R1?

a)

1

b)

2

c)

3

d)

4

7.

A 2.0-ohm resistor and a 4.0-ohm resistor are connected in series with a 12-volt battery. If the current through the 2.0-ohm resistor is 2.0 amperes, the current through the 4.0-ohm resistor is

a)

1.0 A

b)

2.0 A

c)

3.0 A

d)

4.0 A

8.

Two identical lamps, L1 & L2, are connected to a constant voltage power supply. The voltage drop across L1 is 36V. What is the voltage of the power supply?

a)

18V

b)

36V

c)

6V

d)

72V

9.

what is an electric cell?

a)

a device that converts mechanical energy into electrical energy

b)

a device that turns stored chemical energy into electrical energy

c)

a device that devours electrical energy

d)

a device that converts static electricity into mechanical energy

10.

What type of cell is necessary to make solar cells practical?

a)

primary cells

b)

storage cells

c)

none exist that can hold that much energy

11.

Correct

a)

$\epsilon=V+Ir$

b)

$\epsilon=I\left(R+r\right)$

c)

$\epsilon=V$

12.

What is emf?

a)

the electro motive "force" or the force on electrons

b)

the electromotive "force" or the Voltage of a cell measured when there is no current flowing

c)

the electromotive "field" or the Voltage of a cell measured when there is no current

d)

the electromotive "force" or Voltage of a cell measured when connected to a circuit

13.

What is internal resistance?

a)

the resistance inside the cell that increases with more current drawn from the cell

b)

the resistance inside the cell that decreases with more current drawn from the cell

c)

the resistance inside the cell that remains constant as the current drawn from the cell changes

d)

the resistance inside each component which increases as more resistances are added in series

14.

Calculate the emf USING THE GRAPH LINE

a)

1.53 V

b)

1.54 V

c)

0V

d)

1.47 V

15.

If 5 lemons are connected in series and then these 5 are connected to 5 more also in series as a parallel arrangement (5 in parallel with 5) what is the total emf and the total internal resistance?

a)

emf = 10 V, resistance = 1000 ohms

b)

emf = 5 V resistance = 10,000 ohms

c)

emf = 10 V resistance = 1000 ohms

d)

emf = 5V and resistance = 2500 ohms

16.

A lemon has an emf = 1.0 V and internal resistance of 1000 ohms. What is the total internal resistance when 5 lemons are connected in series and the total emf?

a)

5 ohms 5V

b)

5000 ohms 1V

c)

0.2 ohm 5V

d)

2 ohms 1V

17.

A potentiometer wire of length 1 m is connected to a driver cell of emf 3 V as shown in the figure. When a cell of 1×5 V emf is used in the secondary circuit, the balance point is found to be 60 cm. On replacing this cell and using a cell of unknown emf, the balance point shifts to 80 cm.Calculate unknown emf of the cell.

a)

1 V

b)

1.5 V

c)

3 V

d)

2 V

e)

2.2 V

18.

The following graph shows the variation of terminal potential difference V, across a combination of three cells in series to a resistor, versus the current. Calculate the emf and internal resistance of each cell

a)

E = 6 V & r = 3 ohm

b)

E = 2 V & r = 1 ohm

c)

E = 6 V & r = 1 ohm

d)

E = 2 V & r = 3 ohm

e)

E = 1 V & r = 1 ohm

19.

Name the factors decide internal resistance of a cell

a)

1. temperature

b)

2. nature of the electrolyte

c)

3. nature of the electrodes

d)

4.distance between the electrodes

e)

1,2,3 & 4

20.

What is the principle of potentiometer ?

a)

V is proportional to L, when steady current flows through a wire of uniform area of cross section at constant temperature

b)

deflection in G is proportional to current

c)

resistance is proportional to length

d)

resistance is inversely proportional to area of cross section

e)

resistance is proportional to temperature

21.

Calculate the balance point of the cell. Resistance of the potentiometer wire is 20 ohm and length of the wire is 400 cm.

a)

0.75 m

b)

7.5 cm

c)

25 cm

d)

200 cm

e)

300 cm

22.

What happens to the balancing length if the value of the variable resistance R is increased?

a)

decreases

b)

increases

c)

no change

d)

can not predict

23.

Find the potential difference across the 50 ohm resistance?

a)

10 V

b)

5 V

c)

2.5 V

d)

2 V

e)

1 V

24.

What can be reason for one sided deflection in a potentiometer experiment?

a)

Emf of a cell in the primary circuit may be less than that in secondary circuit

b)

Cells in the primary and secondary circuit are connected with opposite terminals

c)

connections may be loose

d)

length of the wire may be too long

25.

If the deflection of the galvanometer increases from A to B, but not zero on reaching B. what could be the reason?

a)

emf of cell in primary circuit may be less compared to that in

secondary

b)

connections may be loose

c)

emf of cell in primary circuit may be more compared to that in

secondary

d)

Cells may be connected with opposite polarity

26.

If the deflection of the galvanometer decreases from A to B, but not zero on reaching B. what could be the reason?

a)

emf of cell in primary circuit may be less compared to that in

secondary

b)

connections may be loose

c)

emf of cell in primary circuit may be more compared to that in

secondary

d)

Cells may be connected with opposite polarity

27.

With K2 closed, if S is increased, how the balancing the length will change?

a)

increases

b)

decreases

c)

no change

d)

may increase or decrease

28.

Potential gradient is .........

a)

V/L

b)

current X resistivity/Area of cross section

c)

inversely proportional to sensitivity

d)

IR

29.

A 3.0 Ω resistor and a 6.0 Ω resistor are connected in parallel.What is their combined resistance?

a)

0.50Ω

b)

2.0Ω

c)

4.5Ω

d)

9.0Ω

30.

The circuit diagram shows a 4.0 Ω resistor and an 8.0 Ω resistor connected to a 6.0V battery.What is the current in the 8.0 Ωresistor?

a)

0 A

b)

0.50A

c)

0.75A

d)

1.0A

31.

The diagram shows a circuit with a 3.0 Ω resistor and a 2.0 Ω resistor connected in parallel. The switch is open, and the ammeter reads 2.0A. The switch is now closed and the ammeter reads the total current in both resistors. What is the ammeter reading with the switch closed?

a)

1.2 A

b)

3.0 A

c)

4.0 A

d)

5.0 A

32.

A 30 Ω resistor is connected in series with another resistor and a 6.0 V battery. The current in the circuit is 0.12 A. A voltmeter is connected across the other resistor. What is the reading on the voltmeter?

a)

2.4 V

b)

3.6 V

c)

6.0 V

d)

9.6 V

33.

Which one of the following resistors connected in parallel with a 24 Ω would give a total resistance of 8 Ω

a)

16 Ω

b)

12 Ω

c)

8 Ω

d)

6 Ω

34.

The speed at which an electron moves in an electric field in a conductor is the

a)

speed of light.

b)

average collision speed.

c)

drift velocity.

d)

average electron speed.

35.

When a current moves through a copper conductor, electrons collide with copper atoms. The result of these collisions is

a)

an increase in voltage.

b)

a decrease in resistance.

c)

an increase in temperature.

d)

a decrease in voltage.

36.

Which factor is least likely to affect the resistance of a conductor?

a)

the length of the conductor

b)

the temperature of the conductor

c)

the overall shape of the conductor

d)

the material the conductor is made from

37.

When a conductor carries a current, the number of conduction electrons that flow in the conductor for 10 s is 3.75 $\times10^{20}$ . What is the current that flows in the conductor?

a)

3.8 A

b)

4.2 A

c)

6.0 A

d)

10 A

38.

A conductor of cross-sectional area 0.10 $mm^2$ carries a current of 2.5 A. If the number of conduction electrons per cubic metre is $1.0\times10^{28\ }$ $m^{-3}$ . What is the value of drift velocity of the free electrons in the conductor?

a)

1.6 $\times10^{-2}\ m\ s^{-1}$

b)

3.9 $\times10^{-2}\ m\ s^{-1}$

c)

3.0 $\times10^{-3\ }m\ s^{-1}$

d)

6.2 $\times10^{-3\ }m\ s^{-1}$

39.

Which statement is true about the drift velocity of the electrons in a current-carrying metallic conductor?

a)

It is directly proportional to the diameter of the conductor.

b)

It is inversely proportional to the current.

c)

It is inversely proportional to the number of conduction electrons per unit volume.

d)

It is directly proportional to the resistance of the conductor if the potential difference across the conductor is kept constant.

40.

A conductor of length 2.0 m and cross-sectional area 5.0 $\times10^{-6}\ m^2$ carries a current of 6.0 A. If the drift velocity of the conduction electrons is 1.5 $\times10^{-4}\ m\ s^{-1}$ , what is the number of electrons in the conductor?

a)

2.5 $\times10^{23}$

b)

2.9 $\times10^{23}$

c)

4.2 $\times10^{23}$

d)

5.0 $\times10^{23}$

41.

A charge of 60 Coulomb flows in a wire for 45 minutes. If the diameter of the wire is 1.0 mm, what is the current density in the wire?

a)

2.2 $\times10^4A\ m^{-2}$

b)

2.8 $\times10^4A\ m^{-2}$

c)

7.6 $\times10^7A\ m^{-2}$

d)

5.6 $\times10^8A\ m^{-2}$

42.

A current flows in a copper wire. The current density in the wire is 1.4 $\times10^6A\ m^{-2}$ . If the number of free electrons in 1 $m^3$ of wire is 8.4 $\times10^{28}$ , what is the drift velocity of the electrons?

a)

1.04 $\times10^{-4}m\ s^{-1}$

b)

3.10 $\times10^{-4}m\ s^{-1}$

c)

1.67 $\times10^{-3}m\ s^{-1}$

d)

1.90 $\times10^{-3}m\ s^{-1}$

43.

A copper wire of length 2.0 m has resistance 20 $\Omega$ . The wire is stretched to an extension of 0.001m. If the volume of the wire remains unchanged, what is the new resistance of the wire?

a)

20.01 $\Omega$

b)

20.02 $\Omega$

c)

20.03 $\Omega$

d)

20.04 $\Omega$

44.

A hollow copper rod has an inner radius of 0.65 cm and an outer radius of 1.0 cm as shown in the diagram. A current flows from P to Q. If the length of the rod is 20 cm and its resistivity is 1.7 $\times10^{-8}\Omega\ m$ , what is the resistance of the copper rod?

a)

3.4 $\times10^{-9}\Omega$

b)

1.9 $\times10^{-5}\Omega$

c)

1.8 $\times10^{-4}\Omega$

d)

2.9 $\times10^{-3}\Omega$

45.

The figure shows a cable which consists of a wire X of resistivity $\rho$ , cross-sectional area A and length $l$ , and four wires of metal Y of resistivity 3 $\rho$ , each with cross-sectional area 2A and of the same length. Find the resistance of this cable in terms of $\rho$ ,A and $l$ .

a)

$\frac{3\rho l}{11A}$

b)

$\frac{7\rho l}{A}$

c)

$\frac{5\rho l}{2A}$

46.

The conductivity of copper is 6.0 $\times10^7\Omega^{-1}m^{-1}.$ The free electron density copper is 8.45 $\times10^{28}m^{-3}$ . Estimate the mean time between collisions of free electrons and positive ions in copper.

a)

2.52 $\times10^{-14}\ s$

b)

4.04 $\times10^{-33}\ s$

c)

4.04 $\times10^{-14}\ s$

d)

7.10 $\times10^{-22}\ s$

47.

What material is a resistor made of?

a)

Graphite

b)

Carbon

c)

Glass

d)

Mica

48.

What is the number value for green in the color code chart?

a)

6

b)

4

c)

2

d)

5

49.

What is the value of a resistor with the colour code: Red, Orange, Green?

a)

234 ohms

b)

20004 ohms

c)

230000 ohms

50.

Write your parents Email address

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Current electricity Revision 12 C

Total questions: 50

Worksheet time: 34mins

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