Current Electricity MCQs Mock Test of Class 12th Physics

Question 1. What is the resistance across A and B in the network in Fig.?

Question 2. When the wires are connected in parallel, the heat produced in the thinner wire is H1 and that in the thicker wire is H2 Then:

Question 3. Two equal resistors are connected in series across a battery and consume a power of P. If these are connected in parallel, then the’ power consumed will be:

Question 4. Thermo electricity was discovered by:

Question 5. Thermo emf is the order of:

Question 6. How many different resistances are possible with two equal resistors?

Question 7. Given three equal resistors, how many different combinations (taken all of them together) can be made?

Question 8. Specific resistance of ali metals is mostly affected by:

Question 9. The example of a non-ohmic resistance is:

Question 10. If a certain piece of copper is to be shaped into a conductor of minimum resistance, its length (L) and cross-sectional area (a) shall respectively be :

Question 11. The specific resistance of a rod of copper as compared to that of thin wire of copper is :

Question 12. A wire of resistance 3 Ω is cut into three pieces, which are then joined to form a triangle. The equivalent resistance between any corners of the triangle is :

Question 13. The length of a conductor is halved. Its resistance will be :

Question 14. In the above question, the conductance:

Question 15. Siemen is the unit of:

Question 16. How much electric energy is consumed by a 100 W lamp used for 6 hours everyday for 30 days?

Question 17. Suppose H1 is the heat generated per second in the filament of a 100 W, 250 V lamp and H2 is the heat generated in the filament of a 200 W, 250 V lamp. Then H1/H2 is equal to:

Question 18. Two wires of copper are of the same length but’have different diameters. When they are connected in series across a battery, the heat generated is H1 When connected in parallel across the same battery, the heat generated during the same time is H2 Then :

Question 19. The speed at which tjie current travels in a conductor is nearly:

Question 20. The resistance of a human body is about:

Question 21. The number of electrons that constitute 1 A of current is:

Question 22. In questions 135, w hen the wires are connected in series, the heat produced in the thinner wire is H1 and that in the thicker wire is H2. Then :

Question 23. Kirchhoffs first and second laws for electrical circuits are consequences of:

Question 24. A 5 A fuse wire can with stand a maximum power of 1 W in circuit. The resistance of the fuse wire is:

Question 25. A galvanometer acting as a volt meter will have with its coil.

Question 26. When three identical bulbs of 60 W, 200 V rating are connected in series to a 200 V supply, the power drawn by them will be:

Question 27. n resistances, each of R Ω, are connected in parallel gives an equivalent resistance of R Ω. If these resistances were , connected in series, the combination would have a resistance in Ω is equal to

Question 28. Why is the Wheatstone bridge more accurate than other methods of measuring resistances: ‘

Question 29. A potential difference of 10 V is applied across a conductance of 2 S. The current in the conductor will be :

Question 30. Ohm’s law is valid when the temperature of conductor is :

Question 31. The emf of a car battery is about:

Question 32. Emf is measured in :

Question 33. 1 kilowatt hour is commonly known as :

Question 34. How many joules are equal to I kWh ?

Question 35. The temperature coefficient of resistance is expressed in :

Question 36. Copper wire is used as connecting wire because :

Question 37. The heat sensitive device whose resistivity changes very rapidly with change of temperature is called a :

Question 38. The phenomenon of super-conductivity was discovered by :

Question 39. The specific resistance of a conductor increases with :

Question 40. In an experiment with potentiometer, null point with a cell is found at 240 cm. When the cell is shunted with a resistance 2 Ω, the null point becomes 120 cm internal resistance of cell is :

Question 41. Two conductors of equal length and radii the ratio of 2 : 3 are; connected in parallel the source of electricity. The ratio of the velocity of electrons in the conductor be :

Question 42. The charge flowing in a conductor varies with time as : q = αt 12 βt² + 16 γt³ Where α, β, γ are positive constants. Then the initial current (l) is given by the condition :

Question 43. In questions 38, the maximum value of current (lmax) is given by the condition :

Question 44. In questions 38, the line (t) after which the value of current reaches a maximum values given by :

Question 45. In following figure shows currents in a part of electrical circuit, then the value of/(in ampere) is given by :

Question 46. The smallest resistance that can be obtained by the combination of n resistors each resistance r is :

Question 47. Which of the following has a negative temperature coefficient of resistance ?

Question 48. An electric heating element consumes 500 W, when connected to a 100 V line. If the line voltage becomes 150 V, the power consumed Will be:

Question 49. A uniform w ire connected across a supply produces heat H per second. If wire is cut into three equal parts and all the parts are connected in parallel across the same supply, the heat produced per second will be :

Question 50. In India electricity is supplied fordomestic use at 220 V. It is supplied at 110 V in U.S.A. If the resistance of a 60 W bulb use in India is R. the resistance of a 60 W bulb for use in USA will be: