MCQs On Direct Current (DC) Electrical Circuit

1) A DC circuit has ___________ as a load.

- Resistance
- Inductance
- Capacitance
- All of the above

2) The purpose of load in an electric circuit is to

- Increase the circuit current
- Utilize electrical energy
- Decrease the circuit current
- None of the above

3) Electrical appliances are not connected in series because

- Series circuit is complicated
- Power loss is more
- Appliances have different current ratings
- None of the above

4) Electrical appliances are connected in parallel because it

- Is a simple circuit
- Draws less current
- Results in reduced power loss
- Makes the operation of appliances independent of each other

5) Three resistance 14.5 Ω, 25.5 Ω and 60 Ω are connected in series across 200 V. What will be the voltage drop across 14.5 Ω

- 29 V
- 13.5 V
- 14 V
- 18 V

6) Two bulbs B_{1} 100 W, 200 V and B_{2} 40 W, 200 V are connected in series across 200 V battery, the total circuit resistance will be

- 1000 Ω
- 400 Ω
- 1400 Ω
- 135 Ω

7) When the number of resistance are connected in parallel, the total resistance is

- Greater than the smallest resistance
- Between the smallest and greatest resistance
- Less than the smallest resistance
- None of the above

8) When cells are arranged in parallel

- The current capacity increases
- The current capacity decreases
- The e.m.f decreases
- The e.m.f increases

9) A cell of e.m.f E is connected across a resistance R. The potential difference between the terminals of the cell is found to be V. The instant resistance of the cell is

- 2(E – V)V/r
- 2(E – V)r/E
- (E – V)r
- ((E – V)/V)r

10) An external resistance R is connected to a cell of internal resistance r. The maximum current flows in the external resistance when

- R < r
- R > r
- R = r
- None of the above

11) A wire has a resistance of 12 Ω. It is bent in the form of a circle. The effective resistance between the two points on any diameter of the circle is

- 6 Ω
- 3 Ω
- 12 Ω
- 24 Ω

12) The total resistance of circuit by connecting 50 resistance of 1/4 Ω in parallel is

- 50/4 Ω
- 4/50 Ω
- 200 Ω
- 1/200 Ω

13) The internal resistance of a cell of e.m.f 2 V is 0.1 Ω. It is connected to a resistance of 3.9 Ω. The voltage across the cell is

- 0.5 V
- 1.95 V
- 1.9 V
- 2 V

14) Three 2 Ω resistors are connected to form a triangle. The resistance between any two corners is

- 6 Ω
- 2 Ω
- (3/4) Ω
- (4/3) Ω

15) A cell with zero internal resistance and e.m.f of 2 V is connected across 2, 3 and 5 Ω. The potential difference across 3 Ω resistor will be

- (2/3) V
- 0.6 V
- 3 V
- 6 V

16) Two bulbs 200 W and 100 W are connected across 220 V supply in series. Find the power consumed by both bulbs

- 300 W
- 200 W
- 66 W
- 50 W

17) An electrical fan and heater are marked as 100 W and 1000 W respectively at 220 V supply. What will be the resistance of heater

- Zero
- Greater than that of the fan
- Less than that of the fan
- Equal to that of the fan

18) If the internal resistance of the cell connected in circuit is greater than the external circuit, higher current will be obtained by arranging cell in ______

- Series
- Parallel
- Series-Parallel
- Any connection

19) The cell e.m.f depends upon

- Internal resistance
- External resistance
- Electrolyte and electrode of the cell
- All of the above

20) How many combination scheme of three resistors can be created

- 2
- 3
- 4
- 5

21) Two resistance in parallel gives combine effect of 6/5 Ω. If one resistance broke, the effective resistance becomes 2 Ω. The broken resistance will be

- 3/5 Ω
- 2 Ω
- 3 Ω
- 6 Ω

22) Two identical resistors connected in series send 10 A through 5 Ω resistor. When same cell connected in parallel sends 8 A. The internal resistance of each cell will be

- 0 Ω
- 5 Ω
- 2.5 Ω
- 7.5 Ω

23) Two batteries of same e.m.f and different internal resistance are connected in series with an external resistance and current is 3 A. When polarity of one is reversed, the current is 1 A. The ratio of e.m.f is

- 2.5
- 2
- 3
- 6

24) When n resistance of r ohm connected in parallel give R total resistance. If all those resistance are connected in series, total resistance will be

- n × R
- R / n
^{2} - n
^{2}× R - R / n

25) Kirchhoff’s current law at a junction deals with

- Conversation of energy
- Conversation of momentum
- Conversation of charge
- Conversation of angular momentum

26) Kirchhoff’s voltage law deals with

- Conversation of energy
- Conversation of momentum
- Conversation of charge
- Conversation of angular momentum

27) What will be the internal resistance of cell, if it supplies 0.9 A current through 2 Ω resistor and 0.3 A current through 7 Ω resistor.

- 0.9 Ω
- 1.2 Ω
- 1 Ω
- 0.5 Ω

28) A battery of 50 V connected across 10 Ω resistor draws 4.5 A current. The internal resistance of the battery is

- 0 Ω
- 5 Ω
- 0.5 Ω
- 4.05 Ω

29) Four cells, each of having internal resistance 1 Ω are connected in parallel. The battery resistance will be

- 4 Ω
- 0.25 Ω
- 2 Ω
- 1 Ω

30) Two voltmeters V_{1} and V_{2} are connected in series across DC source. The V_{1} reads 80 V and has per volt resistance of 200 Ω while V_{2} has a total resistance of 32 kΩ. The line voltage is

- 120 V
- 160 V
- 220 V
- 240 V

31) Resistance 1 Ω, 2 Ω, and 3 Ω are connected in the form of triangle. If a cell of e.m.f 1.5 V and negligible internal resistance is connected across 3 Ω, the current through this resistance will be

- 0.25 A
- 0.5 A
- 1.5 A
- 2.5 A

32) what will be the current in 2 seconds from a wire of having 10 mC charge flow and 2.5 mm cross sectional area.

- 25 mA
- 5 mA
- 20 mA
- 4 mA

33) When two cells whether connected in series or parallel have same current through an external resistance of 2 Ω.What will be their internal resistance.

- 0.5 Ω
- 1 Ω
- 1.5 Ω
- 2 Ω

34) Current divides itself through resistance connected in parallel by

- Inverse ratio of resistance
- Direct ratio of resistance
- Direct ratio of potential
- None of the above

35) If a DC supply delivers maximum power to external resistance. The ratio of its internal and external resistance r/R will be

- 1 : 1
- 1 : 2
- 2 : 1
- 1 : 1/2

36) Two bulb rated at 25 W, 110 V and 100 W, 110 V are connected across 220 V supply. What will happen ?

- 100 W bulb will burn out
- 25 W bulb will burn out
- Both bulb will burn out
- No bulb will burn out

37) Three equal resistors when connected in series dissipates 10 W power, how much power will it dissipates when the same resistors are connected across same potential in parallel.

- 90 W
- 30 W
- 180 W
- 27 W

38) In a circuit two cells of 1.5 V and 2 V e.m.f having internal resistance of 2 Ω respectively are connected in parallel so as to send current in the same direction through an external resistance of 5 Ω. The current will be

- 17/5 A
- 12/5 A
- 5/17 A
- 5/12 A

39) A 40 W bulb is connected in parallel with room heater. What will happen if we turn off bulb ?

- Heater output will increase
- Heater output will decrease
- Heater output will remains same
- None of the above

40) The total conductance of 0.1 S conductance in series is

- 1 S
- 0.1 S
- 0.05 S
- 0.2 S

41) hree conductance G_{1} , G_{2} , G_{3} are connected in parallel. If the total circuit current is 4 A, the current in G_{1} will be

- 1.2 A
- 2 A
- 0.8 A
- 4 A

42) A resistor in a circuit has a value of 560 Ω. It is desired to decrease its value to 344 Ω. The resistance to be connected with it in parallel will be of

- 740 Ω
- 1090 Ω
- 892 Ω
- 540 Ω

43) An ammeter has a resistance of 50 Ω and requires 10 mA for full scale deflection. The shunt resistance S required to allow the meter to measure up to 100 mA is

- 5.56 Ω
- 2.5 Ω
- 15.75 Ω
- 8.75 Ω

- I
^{2}G - I
^{2}/ G - G
^{2}/ I - None of the above

45) Two wires of same properties with having cross sectional area of 3:1 joined together in series. The resistance of thicker wire is 3 Ω. What will be the resistance of thinner wire.

- 5/2 Ω
- 40/3 Ω
- 40 Ω
- 100 Ω

46) The resistance of each arm of Wheatstone bridge is 10 Ω. A resistance of 10 Ω is connected in series with the galvanometer. The equivalent resistance across the battery will be

- 40 Ω
- 20 Ω
- 30 Ω
- 10 Ω

47) If a galvanometer is short circuited in a balanced Wheatstone bridge, the current in various resistors of Wheatstone bridge will

- Increased
- Decreased
- Not change
- Cannot say anything

48) If a galvanometer is open circuited in a balanced Wheatstone bridge, the current in various resistors of Wheatstone bridge will

- Increased
- Decreased
- Not change
- Cannot say anything

49) A resistor of 5 Ω is connected in series with a parallel combination of N number of resistors, each of 5 Ω value. If the total resistance of the circuit is 6 Ω. The number (N) of resistors in parallel will be

- 5
- 10
- 15
- 20

_{1}and r

_{2}are connected in series with an external resistance R. The potential drop across the first cell is found to be zero. The external resistance R is

- r
_{1}+r_{2} - r
_{1}– r_{2} - r
_{2}– r_{1} - r
_{1}r_{2}

51) Two cells whether joined in parallel or series gives the same current when connected to an external resistance of 1 Ω. The internal resistance of each cell will be

- 1 Ω
- 2 Ω
- 4 Ω
- 8 Ω

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