Alternating Current — Physics STD 12 Science — Question

1.6 mA current is flowing in conducting wire then the number of electrons flowing per second is

(a) 1011

(b) 1016

(c) 1019

(d) 1015

Two circular loops of equal radii are placed coaxially at some separation. The first is cut and a battery is inserted in between to drive a current in it. The current c~anges slightly because of the variation in resistance with temperature. During this period, the two loops:

The given figure represents a material which is

(a) Paramagnetic

(b) Diamagnetic

(c) Ferromagnetic

(d) None of these

Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due to:

LEDs have the following advantages over conventional incandescent low power lamps: 

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)

Which one of the following is similar between electrostatic force and gravitational force?

A bar magnet is cut into two equal halves by a plane parallel to the magnetic axis. Of the following physical quantities the one which remains unchanged is:

When the speed of electrons increases, then the value of its specific charge

(a) Increases

(b) Decreases

(c) Remains unchanged

(d) Increases upto some velocity and then begins to decrease

How does the red shift confirms that the universe is expanding

(a) Due to Wien's law	(b) Due to Stefan's law
(c) Due to Kirchhoff's law	(d) Due to Doppler's effect