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Friday, 9 October 2015

D.C. Circuits - Multiple Choice Questions

D.C. Circuits - Multiple Choice Questions Points : direct circuit, D.C. Circuits of electricity multiple choice questions and answers, electrical objective type question answers, mcqs 1. When cells are arranged in equivalent
(i) current capacity increases
(ii) current capacity decreases
(iii e.m.f. increases
(iv) e.m.f. decreases

2. Five cells each of e.m.f. E and internal resistance r are linked in series. If due to error, one cell is connected incorrectly, then equivalent e.m.f. and internal resistance of the combination are
(i) 3E and 5r
(ii) 5E and 5r
(iii) 3E and 3r
(iv) 5E and 4r

3. Three 2 ohm resistors are linked to type a triangle. The resistance among any two corners is
(i) 6Ω
(ii) 2Ω
(iii) (3/4)Ω
(iv) (4/3)Ω

4. The principle of load in an electric circuit is to
(i) increase the circuit current
(ii) utilise electrical energy
(iii) decrease the circuit current
(iv) none of the above

5. Electrical appliance are not attached in series because
(i) series circuit is complex
(ii) power loss is more
(iii) appliances contain different current ratings
(iv) none of the above

6. Electrical appliances are linked in parallel as it
(i) is a simple circuit
(ii) draws less current
(iii) results in reduced power loss
(iv) makes operation of appliances independent of each other

7. The inside resistance of a cell of e.m.f 20 V is 0.1Ω. It is connected to a resistance of 3.9 Ω. Voltage across the cell is
(i) 05 V
(ii) 195 V
(iii) 19V
(iv) 2V

8. D.C. circuit usually has as load.
(i) resistance
(ii) inductance
(iii) capacitance
(iv) both inductance and capacitance

9. When internal resistance of a cell is large compare to external resistance, then high current is obtain through grouping the cells in
(i) series
(ii) parallel
(iii) series-parallel
(iv) all three can be used

10. Wire has a resistance of 12Ω. It is twisted in form of a circle. Effective resistance among two points on any diameter of circle is
(i) 6Ω
(iii) 12Ω
(iv) 24Ω

11. When a number of resistances are attached in parallel, total resistance is
(i) greater than smallest resistance
(ii) between the smallest and greatest resistance
(iii) less than smallest resistance
(iv) none of the above

12. Electric fan and a heater are marked as 100 W, 220 V and 1000 W, 220 V in that order. The resistance of warmer is
(i) zero
(ii) greater than that of fan
(iii) less than that of fan
(iv) equal to that of fan

13. Given three equal resistances. How many combinations of these three resistances an be prepared
(i) three
(ii) four
(iii) five
(iv) two

14. The smallest resistance obtain through connecting 50 resistances of 1/4 ohm each is
(i) 50/4 Ω
(ii) 4/50 Ω
(iii) 200 Ω
(iv) 1/200 Ω

15. A wire of resistance 0.1Ωcm is bent to form a square ABCD of side 10 cm. A parallel wire is connected among B and D to type the diagonal BD, If a 2 V battery of negligible interior resistance a connected among A and C, then total power dissipate Is
(i) 2W
(ii) 3W
(iii) 4W
(iv) 6W

16. A 200 W and 100 W bulb both meant for process at 220 V are attached in series. While connected to a 220 V supply, the power consumed through them is
(i) 66W
(ii) 33W
(iii) 100 W
(iv) 300 W

17. Three cells each of e.m.f. 1.5 V and inner resistance 1 Ω are linked in parallel. The e.m.f. of combination is
(i) 4.5V
(ii) SV
(iii) 3V
(iv) 1.5V

18. The e.m.f. of a cell depends upon
(i) internal resistance
(ii) external resistance
(iii) electrolyte and electrodes of the cell
(iv) none of these factors

19. Two identical cells attached in series send 10 A through 5 Ω resistor. While they are connected in parallel, they send 8 A through similar resistor. The internal resistance of each cell is
(i) zero
(ii) 2.5Ω
(iii) 10Ω
(iv) 1Ω

20. Two resistances are in parallel and give equal resistance of 6/5Ω. One of resistances is broken and the efficient resistance is 2Ω. The resistance of broken resistor is
(iv) 6Ω

21. Two batteries of dissimilar e.m.fs and similar internal resistances are linked in series by an external resistance and current is 3 A. While polarity of one is reversed, the current is 1 A. The ratio of emfs is
(i) 2.5
(ii) 2
(iii) 1.5
(iv) 1

22. In above question, if battery has finite value of inner resistance, then what will be the cause on galvanometer reading?
(i) it will not change
(ii) it will increase
(iii) it will decrease
(iv) data Is insufficient

23. A 50 V battery is attached across 10 Ω resistor. The current is 4.5 A. The internal resistance of battery is
(i) zero
(ii) 5Ω
(iii) 0.5Ω
(iv) 1.1Ω

24. In similar resistors each of resistance r while connected in parallel contain total resistance R. When these resistances are linked in series, the total resistance is
(i) nR
(ii) R/n2
(iii) n2R
(iv) R/n

25. Identical wires of nichrome and copper are joined in series in a circuit. This results in
(i) greater current in nichrome
(ii) greater current in copper
(iii) greater heat in nichrome
(iv) greater heat in copper

26. A cell of small internal resistance and e.m.f. 2 volts is connected to series combination of 2, 3 and 5 ohms. The potential dissimilarity crossways terminals of 3 Ω resistor will be
(i) (2/3) V
(ii) 0.6 V
(ii,) 3V
(iv) 6V

27. In order to get most current in series parallel grouping of cells, external resistance should be the total internal resistance of battery.
(i) less than
(ii) more than
(iii) equal to
(iv) none of above

28. Kirchhoff’s voltage law deals among
(i) conservation of energy
(ii) conservation of charge
(iii) conservation of momentum
(iv) conservation of angular momentum

29. A charge of 10 mC flows through a cross-section 2.5 mm2 normally in 2 seconds. The current is
(i) 25 mA
(ii) 5 mA
(iii) 20mA
(iv) 4mA

30. Kirchhoff’s current law at a junction deals with
(i) conservation of energy
(ii) conservation of momentum
(ii,) conservation of angular momentum
(iv) conservation of charge

31. A cell supplies a current of 0.9 A during 2 Ω external resistance and 0.3 A through 7 Ω external resistance. The internal resistance of the cell is
(i) 0.5Ω
(ii) 1.2Ω
(iii) 1Ω
(iv) 1.5Ω

32. Voltmeters V1 and V2, are linked in series crossways a d.c. line. The voltmeter V1 reads 80 V and has per volt resistance of 200 Ω as V2 has a total resistance of 32 kΩ. The line voltage is
(i) 120V
(ii) 160V
(iii) 220 V
(iv) 240 V

33. Four cell each of internal resistance 1 Ω are linked in parallel. The battery resistance will be
(i) 4Ω
(ii) 0-25Ω
(iii) 2Ω
(iv) 1Ω

34. The current in a coil of resistance 90 Ω is to be bargain by 90%. What value of resistance should be linked in parallel with it?
(i) 9Ω
(ii) 100Ω
(iii) 90Ω
(iv) 10Ω

35. Resistances 1 Ω, 2 Ω and 3 Ω are linked in the form of a triangle. If a cell of e.m.f. 1.5 V and small internal resistance is linked across 3 Ω, the current through this resistor is
(i) 0.25 A
(ii) 0.5 A
(iii) 1.5 A
(iv) 2.5 A

36. A wire has a resistance of 6 ohms. It is bent in form of an equilateral triangle. The effective resistance among any two corners of the triangle is
(i) 4.7 Ω
(ii) 6 Ω
(iii) 4/3 Ω
(iv) 3 Ω

37. Two equal resistances are linked in series across a sure supply. If the resistances are now linked in parallel, the power formed will become
(i) two times
(ii) four times
(iii) one-half
(iv) none of above

38. When resistances are linked in parallel, current divides itself in
(i) direct ratio of resistances
(ii) inverse ratio of resistances
(iii) inverse ratio of potentials
(iv) none of above

39. Two similar cells whether attached in series or in parallel contain the similar current through an external resistance of 2Ω. The internal resistance of each cell is
(ii) 1Ω
(iii) 0.5Ω
(iv) 1.5Ω

40. When a dc. battery of e.m.f. E and internal resistance r delivers utmost power to an external resistance R, the ratio r/R is
(i) 1:1
(ii) 2:1
(iii) 1: 2
(iv) 1: 1/2

41. Three equal resistors linked in series across a source of e.m.f. together dispel 10 W. What would be the power dissipated If the similar resistors are connected in parallel across the similar source of e.m.f.?
(i) 90W
(ii) 30W
(iii) 180 W
(iv) 27 W

42. Two bulbs rated at 25W, 110 V and 100W, 110 V are linked in series to a 220 V supply. What will happen to circuit?
(i) 100 W bulb will burn out
(ii) 5 W bulb will burn out
(iii) both bulbs will burn out
(iv) no bulb will burn out

43. A galvanometer jointly by an unknown resistance in series is linked across two identical batteries each of 1.5 V. When the batteries are connected in series, galvanometer records a currents of 1 A and when batteries are linked in parallel, current is 0.6 A. What is the internal resistance of every battery?
(i) 1Ω
(ii) 0.5Ω
(iii) 1/3Ω
(iv) 1.5Ω

44. An normal dry cell can deliver a current of about
(i) 3A
(ii) 2A
(iii) 1/8A
(iv) none of above

45. A standard 40W tube light is in parallel by a room beater and equally are linked to major supply line. What will happen when light is switched off?
(i) the heater output will increase
(ii) the heater output will decrease
(iii) the heater output will remain same
(iv) none of above

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