NCERT Class 12 MCQ Quiz Hub

Current Electricity Class 12 MCQs Questions

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




2. The resistance of a human body is about:




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




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




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




6. Specific resistance of ali metals is mostly affected by:




7. The example of a non-ohmic resistance is:




8. 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 :




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




10. 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 :




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




12. In the above question, the conductance:




13. Siemen is the unit of:




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




15. 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:




16. 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 :




17. 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 :




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




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




20. The length and radius of an electric resistance of a certain wire are doubled simultaneously, then the:




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




22. 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:




23. 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




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




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




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




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




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




29. The emf of a car battery is about:




30. Emf is measured in :




31. 1 kilowatt hour is commonly known as :




32. How many joules are equal to I kWh ?




33. The temperature coefficient of resistance is expressed in :




34. Copper wire is used as connecting wire because :




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




36. The phenomenon of super-conductivity was discovered by :




37. The specific resistance of a conductor increases with :




38. n 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 :




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




40. 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:




41. 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




42. n 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:




43. Two bulbs 25 W, 220 V and 100 W, 220 V are given. Which has higher resistance?




44. Potentiometer measures the potential difference more accurately than a voltmeter because:




45. In a Wheatstone bridge, the resistance each arm is 10 Ω. If the resistance galvanometers is also 10 Ω, then effective resistance of the bridge will be :




46. A wire P is half the diameter and half the length of a wire Q of similar material. The ratio of resistances of P to that 0 is:




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




48. 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:




49. 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:




50. Thermo electricity was discovered by:




51. Thermo emf is the order of: