Exercise for student: 1. Discharging for 1 time constant is a. 0.65 time of q b. 0.37 time of q c. 1 d. None 2. The energy stored in a charge capacitor a. ½ CV2 b. ½ C2V c. 1/2C/V d. ½ C2V2 3. Capacitor 1 has capacitance C1 and voltage V1. Capacitor 2 has twice the capacitance and the same voltage. If U1 be the energy of C1, the energy U2 of capacitor 2 is a. 2 U1 b. 4 U1 c. U1/2 d. U1/4 4. Assuming the earth as a sphere of radius R = 6400 km, the capcaticance of the earth is. a. infinite b. zero c. 711 d. 171 5. A parallel plate capciator is charged to potential V . The distance between the plates is d. the intensity of electric field between the plates is E. Now if the distance between the plates is increased to 2d. the electric field will be. a. E b. 2E c. E/2 d. None 6. An air capacitor C connected to a battery of e.m.f V acquires a charge q and energy E. The capcitor C is disconnected from the battery and a dielectric slab is placed between the plates, The charges on the plates. a. increases b. decreases c. remains same d. None 7. A capacitor works in: a. AC circuit b. DC circuit c. both the circuit d. neither in AC nor in DC circuit 8. A parallel plate capacitor is made by stacking n equally spaced plates connected alternately. If the capacitance between any two plates is C, then the resulting capacitance is: a. C b. nC c. (n-1) C d. (n+1)C 9. If E is the electric field intensity of an electrostatic field, then the electrostatic energy density is proportional to: a. E b. E2 c. 1/E2 d. E3 10. The capacity of a conductor does not depend upon: a. charge b. voltage c. nature of material d. all 11. The energy stored in a condenser is in the form of: a. kinetic energy b. potential energy c. elastic energy d. magnetic energy 12. A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor: a. increases b. decreases c. becomes infinite d. remains unchanged 13. Two capacitors 2 F and 4 F are connected in parallel. A third capacitor of 6 C capacity is connected in series. The combination is then connected across a 12V battery. The voltage across 2 F capacity is: a. 2V b. 6V c. 8V d. 1V 14. In order to obtain a time constant of 10s in an RC circuit containing a resistance of 1000 , the capacity of a condenser should be: a. 10 F b. 100 F c. 1000 F d. 10,000 F 15. Three capacitors of capacitances 3 F, 9 F and 18 F are connected once in series and another time in parallel. The ratio of equivalent capacitances in two cases (Cs /Cp) will be: a. 1:15 b. 15:1 c. 1:1 d. 1:3 16. Capacitors are used for: a. smoothing rectified across from power supplies b. elimination of sparking in switches c. storing large quantities of charge for use in research such as nuclear fusion d. all 17. If the upper plate of the parallel plate condenser is connected to the lower plate, then its capacitance becomes a. zero b. increases c. decreases d. infinity 18. If a dielectric is introduced in plates of a capacitor, what will happen to the capacitance of a capacitor a. increases b. decreases c. unaffected d. zero 19. Due to polarization, potential difference across the plates of a capacitor a. increases b. decreases c. constant d. none of these 20. When the voltage across a capacitor is increased, the stored charge a. increase b. Decrease c. Constant d. None 21. The distance between the plates of capacitor is decreased. The capacity of it is a. Increased b. Decreased c. Constant d. none 22. The capacitance of a capacitor does not depends upon, a. area of plates b. distance between the plates c. medium between the plates d. charge on the plates 23. For three capacitors of different values connected in parallel with a battery, each capacitor gets a. different charges & different potential difference b. same charge & different potential difference c. same charge & same potential difference d. different charge & same potential difference 24. For a given potential difference the energy stored in a parallel plate capacitor is directly proportional to the a. area of the plates b. material of the plates c. separation between the plates d. none 25. A 5M resistor is connected with a capacitor of 2 value. The time constant of the circuit is a. 0.1s b. 1s c. 10s d. 2.5s 26. When a capacitor of capacitance 4 and a potential difference of 100V in completely discharged, the energy released is a. 0.01J b. 0.02J c. 0.03J d. 0.04J 27. Farad is the unit of a. charge b. current c. electric flux d. none 28. Which of the following unit is different from the other? a. electron volt b. watt-hour c. joule d. volt 29. A parallel plate capacitor has a capacitance of 50 in air and 100 when immersed in oil. The dielectric constant of the oil is: a. 0.5 b. 1.0 c. 1.5 d. 2.0 30. If the distance between parallel plates of a capacitor is halved and dielectric constant is doubled then the capacitance: a. decreases two times b. increases two times c. increases four times d. remains the same
Posted on: Sat, 03 Aug 2013 15:18:05 +0000
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