Electromagnetic Waves — Physics STD 12 Science — Question

A proton, a deuteron and an α - particle having the same kinetic energy are moving in circular trajectories in a constant magnetic field. If   and   denote respectively the radii of the trajectories of these particles, then

(a)

(b)

(c)

(d)

Assertion :   Mass of moving photon varies inversely as the wavelength.

Reason     : Energy of the particle = Mass ×

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Let I_A and I_B be moments of inertia of a body about two axes A and B respectively. The axis A passes through the centre of mass of the body but B does not:

1. I_A < I_B.
2. If I_A < I_B, the axes are parallel.
3. If the axes are parallel, I_A < I_B.
4. If the axes are not parallel I_A > I_B.

The filament of an electric bulb is made of:

Consider a binary star system consisting of two stars of masses  and  separated by a distance of 30 AU with a period of revolution equal to 30 years. If one of the two stars is 5 times farther from the centre of mass than the other. The masses of the two stars in terms of solar masses are

(a) 5, 15

(b) 25, 5

(c) 25, 10

(d) 7, 25

Why is gold used in the Gold-leaf electroscope?

If there were only one type of charge in the universe, then

In Young's double slit experiment how many maximas can be obtained on a screen (including the central maximum) on both sides of the central fringe if λ = 2000 and d = 7000  

(a) 12

(b) 7

(c) 18

(d) 4

When current passes through the circuit a compass needle rests in which direction (with respect to the Earth)?

In the electrolysis of NaCl: