Atoms — Physics STD 12 Science — Question

Energy production in nuclear reactor is due to :

Semiconductor is damaged by the strong current due to

(a) Lack of free electron	(b) Excess of electrons
(c) Excess of proton	(d) None of these

If the wavelength of red light in air is 7500 A, then the frequency of light in air is.

A circular loop has a radius of 5 cm and it is carrying a current of 0.1 amp. Its magnetic moment is

(a) 1.32	(b) 2.62
(c) 5.25	(d) 7.85

A parallel plate capacitor of plate area A has a charge Q. The force on each plate of the capacitor is

The current through an ideal PN-junction shown in the following circuit diagram will be

(a) Zero

(b) 1 mA

(c) 10 mA

(d) 30 mA

Two like magnetic poles of strength 10 and 40 SI units are separated by a distance 30 cm. The intensity of magnetic field is zero on the line joining them

(a) At a point 10 cm from the stronger pole

(b) At a point 20 cm from the stronger pole

(c) At the mid-point

(d) At infinity

If the direction of the initial velocity of the charged particle is neither along nor perpendicular to that of the magnetic field, then the orbit will be

(a) A straight line

(b) An ellipse

(c) A circle

(d) A helix

The ratio of de-Broglie wavelength of a a-particle to that of a proton being subjected to the same magnetic field so that the radii of their path are equal to each other assuming the field induction vector   is perpendicular to the velocity vectors of the a-particle and the proton is

(a) 1

(b)

(c)

(d) 2