Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Out of the following statements which is not correct

(a) When unpolarised light passes through a Nicol's prism, the emergent light is elliptically polarised

(b) Nicol's prism works on the principle of double refraction and total internal reflection

(c) Nicol's prism can be used to produce and analyse polarised light

(d) Calcite and Quartz are both doubly refracting crystals

A hank of uninsulated wire consisting of seven and a half turns is stretched between two nails hammered into a board to which the ends of the wire are fixed. The resistance of the circuit between the nails is determined with the help of electrical measuring instruments. Determine the proportion in which the resistance will change if the wire is unwound so that the ends remain to be fixed to the nails.

A proton, a deutron and an a-particle having the same momentum, enters a region of uniform electric field between the parallel plates of a capacitor. The electric field is perpendicular to the initial path of the particles. Then the ratio of deflections suffered by them is

(a) 1 : 2 : 8

(b) 1 : 2 : 4

(c) 1 : 1 : 2

(d) None of these

A photodetector is made from a semiconductor In _0.53Ga _0.47As with E_g = 0.73 eV. What is the maximum wavelength, which it can detect

(a) 1000 nm

(b) 1703 nm

(c) 500 nm

(d) 173 nm

If a bar magnet of magnetic moment M is freely suspended in a uniform magnetic field of strength B, the work done in rotating the magnet through an angle θ is

(a) MB(1- sinθ

(b) MB sinθ

(c) MB cosθ

(d) MB(1 – cosθ)

Assertion  :  The unpolarised light and polarised light can be distinguished from each other by using polaroid.

Reason      : A polaroid is capable of producing plane polarised beams of light.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

The mutual inductance between two coils is 1.25 henry. If the current in the primary changes at the rate of 80 ampere/second, then the induced e.m.f. in the secondary is

(a)  12.5 V

(b) 64.0 V

(c)  0.016 V

(d) 100.0 V

The shortest wavelength in the Lyman series of hydrogen spectrum is 912 Å corresponding to a photon energy of 13.6 eV. The shortest wavelength in the Balmer series is about

(a) 3648 Å

(b) 8208 Å

(c) 1228 Å

(d) 6566 Å

The angle of minimum deviation for a prism is 40° and the angle of the prism is 60°. The angle of incidence in this position will be

(a) 30°

(b) 60°

(c) 50°

(d) 100°