Electromagnetic Waves — Physics STD 12 Science — Question

A magnet when placed perpendicular to a uniform field of strength   experiences a maximum couple of moment 4 . What is its magnetic moment

(a) 0.4

(b) 0.2

(c) 0.16

(d) 0.04

A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west at the same distance the magnetic field at P is:

A charge Q is uniformly distributed over a large plastic plate. The electric field at a point P close to the centre of the plate is 10Vm^-1. If the plastic plate is replaced by a copper plate of the same geometrical dimensions and carrying the same charge Q, the electric field at the point P will become:

The electrostatic potential on the surface of a charged conducting sphere is 100V. Two statements are made in this regard S₁ at any point inside the sphere, electric intensity is zero. S₂ at any point inside the sphere, the electrostatic potential is 100V. Which of the following is a correct statement?

The radioactive nucleus  decays to   through the emission of

(a) Neutron

(b) Proton

(c) Electron

(d) Positron

A galvanometer of resistance 20 W is to be converted into an ammeter of range 1 A.  If a current of 1 mA produces full scale deflection, the shunt required for the purpose is

(a) 0.01 W

(b) 0.05 W

(c) 0.02 W

(d) 0.04 W

If the kinetic energy of a free electron doubles, its de-Broglie wavelength changes by the factor

(a)

(b)

(c)

(d) 2

For a crystal system, a = b = c, a = b = g  ¹ 90^o, the system is

(a) Tetragonal system	(b) Cubic system
(c) Orthorhombic system	(d) Rhombohedral system

Which radiation in sunlight, causes heating effect

(a) Ultraviolet

(b) Infrared

(c) Visible light

(d) All of these

When a beam of light is used to determine the position of an object, the maximum accuracy is achieved if the light is

(a) Polarised	(b) Of longer wavelength
(c) Of shorter wavelength	(d) Of high intensity