Electromagnetic Waves — Physics STD 12 Science — Question

In a transformer, the coefficient of mutual inductance between the primary and the secondary coil is 0.2 henry. When the current changes by 5 ampere/second in the primary, the induced e.m.f. in the secondary will be

(a)  5 V

(b) 1 V

(c)  25 V

(d) 10 V

The dependence of binding energy per nucleon,  on the mass number, A, is represented by

(a)

(b)

(C)

(d)

Two plates of parallel plate capacitor are joined inside with metal rod. The capacitance of a capacitor is __________ .

Figure shows two capacitors connected in series and joined to a battery. The graph shows the variation in potential as one moves from left to right on the branch containing the capacitors:

1. C₁ > C₂
2. C₁ = C₂
3. C₁ < C₂
4. The information is not sufficient to decide the relation between C₁ and C₂.

The apparent wavelength of the light from a star moving away from the earth is 0.01% more than its real wavelength. Then the velocity of star is

(a) 60 km/sec

(b) 15 km/sec

(c) 150 km/sec

(d) 30 km/sec

Assertion  :  A current I flows along the length of an infinitely long straight and thin walled pipe. Then the magnetic field at any point inside the pipe is zero.

Reason      :   

(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.

Mark out the correct options.

1. The energy of any small part of a string remains constant in a travelling wave.
2. The energy of any small part of a string remains constant in a standing wave. 
3. The energies of all the small parts of equal length are equal in a travelling wave.
4. The energies of all the small parts of equal length are equal in a standing wave.

The idea of matter waves was given by

(a) Davisson and Germer

(b) de-Broglie

(c) Einstein

(d) Planck

In a PN junction:

A coil having N turns carry a current I as shown in the figure. The magnetic field intensity at point P is

(a)

(b)

(c)

(d) Zero