Electric Charges and Fields — Physics STD 12 Science — Question

Which law can ampere’s circuital be derived from?

Two protons are kept at a separation of 10nm. Let F_n and F_e be the nuclear force and the electromagnetic force between them:

1. F_e = F_n.
   
2. F_e >> F_n.
   
3. F_e << F_n.
   
4. F_e and F_n differ only slightly.
   

In a certain double slit experimental arrangement interference fringes of width 1.0 mm each are observed when light of wavelength 5000 Å is used. Keeping the set up unaltered, if the source is replaced by another source of wavelength 6000 Å, the fringe width will be

(a) 0.5 mm

(b) 1.0 mm

(c) 1.2 mm

(d) 1.5 mm

The ratio of the number of electrons and holes in intrinsic semiconductors at normal temperature is :

In a Young’s double slit experiment, the separation of the two slits is doubled. To keep the same spacing of fringes, the distance D of the screen from the slits should be made

(a)

(b)

(c) 2D

(d) 4D

A motor having an armature of resistance 2Ω is designed to operate at 220 V mains. At full speed, it develops a back e.m.f. of 210V. When the motor is running at full speed, the current in the armature is

(a) 5A

(b) 105A

(c) 110A

(d) 215A

Generation, propagation and detection of electromagnetic waves is the basis of:

PN-junction diode works as a insulator, if connected

(a) To A.C.

(b) In forward bias

(c) In reverse bias

(d) None of these

The dimensions of polarisation are:

Velocity of sound in air is 332m/s. Its velocity in vacuum will be:

1. > 332m/s
2. = 332 m/s
3. < 332m/s
4. Meaningless.