Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

Two capacitors of 3pF and 6pF are connected in series and a potential difference of 5000 V is applied across the combination. They are then disconnected and reconnected in parallel. The potential between the plates is

(a) 2250 V

(b) 2222 V

(c) 2.25

(d) 1.1

In an insulator, the forbidden energy gap between the valence band and conduction band is of the order of:

The fact that electric charges are integral multiples of the fundamental electronic charge was proved experimentally by

(a) Planck

(b) J.J. Thomson

(c) Einstein

(d) Millikan

In the figure shown, the total resistance between A and B is

(a) 12 Ω

(b)  4 Ω

(c)  6 Ω

(d) 8 Ω

A parallel plate air capacitor is charged to a potential difference of V. After disconnecting the battery, distance between the plates of the capacitor is increased using an insulating handle. As a result, the potential difference between the plates

(a) Decreases

(b) Increases

(c) Becomes zero

(d) Does not change

The time period of oscillation of a magnet in a vibration magnetometer is 1.5 seconds. The time period of oscillation of another magnet similar in size, shape and mass but having one-fourth magnetic moment than that of first magnet, oscillating at same place will be

(a) 0.75 sec

(b) 1.5 sec

(c) 3 sec

(d) 6 sec

The current in a conductor varies with time t as  where I is in ampere and t in seconds.  Electric charge flowing through a section of the conductor during t = 2 sec to t = 3 sec is

(a) 10 C

(b) 24 C

(c) 33 C

(d) 44 C

If a dielectric substance is introduced between the plates of a charged air-gap capacitor. The energy of the capacitor will

(a) Increase	(b) Decrease
(c) Remain unchanged	(d) First decrease and then increase

Energy bands in solids are a consequence of

(a) Ohm’s Law	(b) Pauli’s exclusion principle
(c) Bohr’s theory	(d) Heisenberg’s uncertainty principle

The thermal radiation emitted by a body is proportional to Tⁿ where Tis its absolute temperature. The value of n is exactly 4 for:

1. A blackbody.
2. All bodies.
3. Bodies painted black only.
4. Polished bodies only.