Magnetism And Matter — Physics STD 12 Science — Question

If the potential difference applied to an X-ray tube is increased, then for the emitted radiation :

In a parallel beam of white light is incident on a converging lens, the colour which is brought to focus nearest to the lens is

(a) Violet	(b) Red
(c) The mean colour	(d) All the colours together

In a YDSE bi-chromatic light of wavelengths 400 nm and 560 nm are used. The distance between the slits is 0.1 mm and the distance between the plane of the slits and the screen is 1m. The minimum distance between two successive regions of complete darkness is

(a) 4 mm

(b) 5.6 mm

(c) 14 mm

(d) 28 mm

The work done by the external forces on a system equals the change in:

1. Total energy.
2. Kinetic energy.
3. Potential energy.
4. None of these.

A. Current flow inside the capacitor due to accumulation of charges on the capacitor walls is called displacement current.
B. Current due to the flow of electrons due to some potential difference is called as conduction current. 
C. Displacement current came into existence when Maxwell observed that if a magnetic compass is placed between the capacitors the needle gets deflected which signifies presence of magnetic fields which would possibly caused due to some changing current.
D. Displacement current change the actual motion of electric charges.
Which of the above statement(s) is/ are correct?

If in a nuclear fusion process the masses of the fusing nuclei be  and   and the mass of the resultant nucleus be , then

(a)

(b)

(c)

(d)

An electric bulb is made to work at 12 V dc. When this bulb is joined with an ac source, it gives normal brightness. Peak voltage of ac source is:

The production of e.m.f. by maintaining a difference of temperature between the two junctions of two different metals is known as

(a) Joule effect

(b) Seebeck effect

(c) Peltier effect

(d) Thomson effect

The reason for the energy associated with a moving charge is: