Atoms — Physics STD 12 Science — Question

The simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons. This is because:

If a power of 100 W is being supplied across a potential difference of 200 V, current flowing is(a) 2 A(b) 0.5 A(c) 1 A(d) 20 A

1 micro farad =

As the temperature of hot junction increases, the thermo e.m.f.(a) Always increases(b) Always decreases(c) May increase or decrease(d) Always remains constant

What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other(a) 60°(b) 90°(c) 120°(d) 175°

An electric dipole is placed at the centre of a sphere.
Mark the correct options:

1. The flux of the electric field through the sphere is zero.
2. The electric field is zero at every point of the sphere.
3. The electric field is not zero anywhere on the sphere.
4. The electric field is zero on a circle on the sphere.

Mark the correct options:

1. If the far point goes ahead, the power of the divergent lens should be reduced.
2. If the near point goes ahead, the power of the convergent lens should be reduced.
3. If the far point is 1 m away from the eye, divergent lens should be used.
4. If the near point is 1 m away from the eye, divergent lens should be used.

An antenna is a device (a) That converts electromagnetic energy into radio frequency signal(b) That converts radio frequency signal into electromagnetic energy(c) That converts guided electromagnetic waves into free space electromagnetic waves and vice-versa(d) None of these