Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A bar magnet is cut into two equal halves parallel to its magnetic axis. The physical quantity that remains unchanged is:

The optical path of a monochromatic light is same if it goes through 4.0 cm of glass or 4.5 cm of water.  If the refractive index of glass is 1.53, the refractive index of the water is

(a) 1.30

(b) 1.36

(c) 1.42

(d) 1.46

A radioactive material has a half-life of 8 years. The activity of the material will decrease to about 1/8 of its original value in

(a) 256 year

(b) 128 year

(c) 64 year

(d) 24 year

An electron, a proton, a deuteron and an alpha particle, each having the same speed are in a region of constant magnetic field perpendicular to the direction of the velocities of the particles. The radius of the circular orbits of these particles are respectively R_e, R_p, R_d and R_a. It follows that

(a)

(b)

(c)

(d)

In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is

(a) 36

(b) 26

(c) 16

(d) 6

In which of the following is the interference due to the division of wave front

(a) Young's double slit experiment	(b) Fresnel's biprism experiment
(c) Lloyd's mirror experiment	(d) Demonstration colours of thin film

Which of the following graphs may represent the relation between the capillary rise h and the radius r of the capillary?

An electron makes a transition from orbit n = 4 to the orbit n = 2 of a hydrogen atom. The wave number of the emitted radiations (R = Rydberg's constant) will be

(a)

(b)

(c)

(d)

A heater draws a current of 2A when connected to a 250V source. The rate of energy dissipation is

(a) 500 W

(b) 1000 W

(c) 250 W

(d) 125 W

In a plane electromagnetic wave the phase difference between electric and magnetic field vectors is :