Alternating Current — Physics STD 12 Science — Question

A beam with wavelength  falls on a stack of partially reflecting planes with separation d. The angle q that the beam should make with the planes so that the beams reflected from successive planes may interfere constructively is (where n = 1, 2, ……)

(a)

(b)

(c)

(d)

If light is passed through a double-slit opening and falls onto a screen, Identify the pattern produced on the screen.

A moving coil galvanometer has N number of turns in a coil of effective area A, it carries a current I. The magnetic field B is radial. The torque acting on the coil is:

The region of the atmosphere above troposphere is known as

(a) Lithosphere

(b) Uppersphere

(c) Ionosphere

(d) Stratosphere

Electric charges q, q, -2q are placed at the corners of an equilateral triangle ABC of side l. The magnitude of electric dipole moment of the system is

(a) ql

(b) 2ql

(c)

(d) 4ql

Ionisation energy of 10 times ionised sodium atom will be :

An electromagnetic wave propagating along north has its electric field vector upwards. Its magnetic field vector point towards.

Which of the following is not a correct statement

(a) Resistivity of electrolytes decreases on increasing temperature

(b) Resistance of mercury falls on decreasing its temperature

(c) When joined in series a 40 W bulb glows more than a 60 W bulb

(d) Resistance of 40 W bulb is less than the resistance of 60 W bulb

What is the purpose of anode in a Cathode ray tube?

Thermal neutrons can cause fission in

(a)

(b)

(c)

(d)