Atoms — Physics STD 12 Science — Question

Potentiometer measures potential more accurately because:

If no external voltage is applied across P-N junction, there would be

(a) No electric field across the junction

(b) An electric field pointing from N-type to P-type side across the junction

(c) An electric field pointing from P-type to N-type side across the junction

(d) A temporary electric field during formation of P-N junction that would subsequently disappear

Two point charges + Q and + q are separated by a certain distance. If + Q > + q then in between the charges the electric field is zero at a point.

A particle is projected in a plane perpendicular to a uniform magnetic field. The area bounded by the path described by the particle is proportional to:

1. The velocity.
2. The momentum.
3. The kinetic energy.
4. None of these.

The free electron density is more in .....:

A long, straight wire carries a current i. The magnetizing field intensity H is measured at a point P close to the wire. A long, cylindrical iron rod is brought close to the wire so that the point P is at the centre the rod. The value of H at P will:

The energy of an X- ray photon of wavelength 1.65 Å is (h = 6.6 , 1eV = 1.6

(a)  3.5 keV

(b) 5.5 keV

(c) 7.5 keV

(d) 9.5 keV

The Einstein’s photo-electric equation is based upon the conservation of:

The binding energy per nucleon of iron atom is approximately.

A certain amount of current when flowing in a properly set tangent galvanometer, produces a deflection of 45°. If the current be reduced by a factor of , the deflection would

(a) Decrease by 30°

(b) Decrease by 15°

(c) Increase by 15°

(d) Increase by 30°