STUDY MATERIAL : QUESTION BANK FOR STUDENTS OF CLASS XII CBSE (Science)

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : CURRENT ELECTRICITY
1. Two 120 V bulbs , one of 25 W and the other of 200W were connected in series across a240 V line. One bulb burnt out instantaneously. Which one has burnt and why?
2. Out of two bulbs one marked 25 W and the other marked 100 W, which has greater resistance?
3. A metallic conductor is at a temperture T1. The temperature is now increased to T2. How will the product of its resistivity and conductivity change?
4. What is the largest voltage you can safely apply across a resistor marked 196Ω - 1 W?
5. Which has greater resistance, 1kW electric heater or a 100W electric bulb?
6. State the condition in which the terminal voltage across a secondary cell is greater than its emf.
7. If the temperature of a good conductor increases, how does the relaxation time of electron in the conductor change?
8. The car battery is of 12 V. Eight dry cells can be connected in series to get 12V. But such arrangement is not used in starting a car. Why?
9. What is the effect of heating on the drift velocity of electrons in a conductor?
10. A uniform wire is cut into half and the pieces are joined in parallel. What is the ratio of the new resistance to that of the uncut wire?
11. What is a shunt?
12. How can we increase the sensitivity of a potentiometer?
13. How does the resistance of a wire depend on the amount of current flowing through it?

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : DUAL NATURE OF MATTER AND RADIATION

1. How will the photoelectric current change on decreasing the wavelength of incident radiation for a given photosensitive material?
2. Why alkali metals are most suitable for photoelectric emission?
3. What si the rest mass of a photon?
4. O what factor does the energy carried by a photon depend?
5. Explain the laws of photoelectric emission on the basis of Einstein's equation of photoelectric effect.

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : ELECTROMAGNETIC WAVES

1. Why are microwaves used in RADAR?
2. Which part of the electromagnetic spectrum has the largest penetrating power?
3. What is common to all electromagnetic waves?
4. What oscillates in an electromagnetic wave of frequency 10 MHz?
5. What is the ratio of the speeds of gamma rays and infrared rays in vacuum?
6. Transmission of TV signals is not possible using sky waves. Why?
7. Why do accelerated charges produce em waves?

QUESTION BANK FOR STUDENTS OF CLASS XII CBSE : ELECTROSTATICS

1. What orientation of an electric dipole in a uniform electric field corresponds to its stable equilibrium?
2. What is the ratio of electric field intensities at any two points between the plates of a parallel plate capacitor?
3. Draw an equipotential surface for a point charge qith Q>0.
4. What is the amount of work done in moving a 100 nC charge between two points 5cm apart on an equipotential surface?
5. How does the force between two point charges change if the dielectric constant of the medium in which they are kept increases?
6. Name the Physical quantity whose SI unit is
i) newton/coulomb
ii) joule/coulomb

7. In a medium, the force of attraction between two point electric charges. distance d apart is F. What distance apart should these be kept in the same medium so that the force between them becomes 
i) 3F
ii) F/3

8. Define 'dielectric constant' of a medium in terms of force between electric charges.
9. In which direction does the electric potential decrease in a uniform electrostatic field?
10. Draw graph showing variation of electric field with distance for a uniformly charged metallic sphere.
11. write down dimensional formula for K (*the proportionality constant in Coulomb's law)
12. What will be the dimensional formula for electric field?
13. For what orientation does an electric dipole experience a zero torque but non zero force in a non uniform electric field?
14. Define dielectric strength of a medium.
15. Show graphically the variation of charge Q with time t when a condensor (capacitor) is charged.
16. Two point charges, q1 and q2 at a separation r in vacuum exert a force F on each other. What should be their separation in an oil of relative permitivity 16 so that the force between them remains F only.
17. What should be the charge on a sphere of radius 2 cm so that when it is brought in contact with another sphere of radius 5cm carrying a charge of 10 microcoulomb, there is no net transfer of charge between the spheres.
18. The dielectric constant of a medium is unity. What will be its permitivity?

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