Electromagnetic Waves — Physics STD 12 Science — Question

A metal sheet is placed in front of a strong magnetic pole. A force needed to:

A laser beam of pulse power 10¹² watt is focussed on an object are 10^–4 cm². The energy flux in watt/ cm² at the point of focus is

(a) 1020

(b) 1016

(c) 108

(d) 104

The spectrum of radiation 1.0   is in the infrared region. The energy of one photon of this in joules will be

(a) 6.62

(b) 6.62

(c)

(d) 3

The electric potential V at any point O (x, y, z all in metres) in space is given by . The electric field at the point (1m,0, 2m)  in volt/metre  is

(a) 8 along negative X - axis	(b) 8 along positive X -  axis
(c) 16 along negative X -  axis	(d) 16 along positive Z - axis

What is the unit of surface charge density in the SI unit?

An attractive force of 9N acts between +5C and −5C at some distance. These charges are allowed to touch each other and are then again placed at their initial position. The force acting between them will be:

If the strength of the magnetic field produced 10cm away from a infinitely long straight conductor is  , the value of the current flowing in the conductor will be

(a) 5 ampere

(b) 10 ampere

(c) 500 ampere

(d) 1000 ampere

The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0 ×   cm is

(a) 80 volts

(b) 8  volts

(c) 9 volts

(d) 9  volts

Red light is generally used to observe diffraction pattern from single slit. If blue light is used instead of red light, then diffraction pattern

(a) Will be more clear	(b) Will contract
(c) Will expanded	(d) Will not be visualized

A charge produces an electric field of 1 N/C at a point distant 0.1 m  from it. The magnitude of charge is

(a) 1.11

(b) 9.11

(c) 7.11

(d) None of these