Electric Charges and Fields — Physics STD 12 Science — Question

In Young’s experiment, the ratio of maximum to minimum intensities of the fringe system is 4 : 1. The amplitudes of the coherent sources are in the ratio

(a) 4 : 1

(b) 3 : 1

(c) 2 : 1

(d) 1 : 1

In a transformer the primary has 500 turns and secondary has 50 turns. 100 volts are applied to the primary coil, the voltage developed in the secondary will be

(a) 1 V

(b) 10 V

(c) 1000 V

(d) 10000 V

A wire in the form of a circular loop of one turn carrying a current produces a magnetic field B at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is

(a)  5B

(b) 3B

(c) 2B

(d) 4B

The ionization potential for second He electron is

(a) 13.6 eV

(b) 27.2 eV

(c) 54.4 eV

(d) 100 eV

Effective capacitance between A and B in the figure shown is (all capacitance are in mF)

(a) 21 mF

(b) 23 mF

(c) F

(d)

The average e.m.f. induced in a coil in which a current changes from 0 to 2 A in 0.05 s is 8 V. The self inductance of the coil is

(a) 0.1 H

(b) 0.2 H

(c) 0.4 H

(d) 0.8 H

Equal charges are located at three corners of an equilateral triangle. The true statement for electric potential V and electric field intensity E at the centre O of the triangle will be:

In a parallel beam of white light is incident on a converging lens, the colour which is brought to focus nearest to the lens is

(a) Violet	(b) Red
(c) The mean colour	(d) All the colours together

What is the path difference of destructive interference

(a) nl

(b) n(λ  + 1)

(c)

(d)