Wave Optics — Physics STD 12 Science — Question

Current in a circuit falls from 5.0 A to 0.0 A in 0.1 s . If an average emf of 100 V induced then the value of self inductance of the circuit is ___________ .

A charge (-q) and another charge (+Q) are kept at two points A and B respectively. Keeping the charge (+Q) fixed at B, the charge (-q) at A is moved to another point C such that ABC forms an equilateral triangle of side l. The net work done in moving the charge (-q) is

(a)

(b)

(c)

(d) Zero

Statement A: With an increase in the frequency of AC supply inductive reactance increases.
Statement B: With an increase in the frequency of AC supply capacitive reactance increase.

Choose the correct option:

The EMF of a cell can be defined as:

Which of the following is most suitable for the core of electromagnets

(a) Soft iron

(b) Steel

(c) Copper-nickel alloy

(d) Air

Force between two identical bar magnets whose centres are r metre apart  is 4.8 N, when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to

(a) 2.4N

(b) 1.2N

(c) 0.6N

(d) 0.3N

When current is passed in antimony-bismuth couple, then

(a) The junction becomes hot when the current is from bismuth to antimony

(b) The junction becomes hot when current flows from antimony to bismuth

(c) Both junctions become hot

(d) Both junctions become cold

The figure shows a double slit experiment P and Q are the slits. The path lengths PX and QX are nλ and (n+2)λ  respectively, where n is a whole number and λ is the wavelength. Taking the central fringe as zero, what is formed at X

(a) First brigh

(b) First dark

(c) Second bright

(d) Second dark