Alternating Current — Physics STD 12 Science — Question

Solar energy is mainly caused due to

(a) Fission of uranium present in the sun

(b) Fusion of protons during synthesis of heavier elements

(c) Gravitational contraction

(d) Burning of hydrogen in the oxygen

Electric charges of +10μC, + 5μC, -3μC and +8 μC  are placed at the corners of a square of side  m. the potential at the centre of the square is

(a) 1.8 V

(b)  V

(c) 1.8

(d) 1.8  V

The avalanche breakdown in p-n junction is due to:

Two equal positive charges are kept at points A and B. The electric potential at the points between A and B (excluding these points) is studied while moving from A to B. The potential.

1. Continuously increases.
2. Continuously decreases.
3. Increases then decreases.
4. Decreases then increases.

In an A.C. circuit the voltage is V, and current is I, then power loss will be :

The mutual inductance of an induction coil is 5H. In the primary coil, the current reduces from 5A to zero in  . What is the induced emf in the secondary coil

(a) 2500 V

(b) 25000V

(c) 2510V

(d) Zero

A wave is propagating in a medium of electric dielectric constant 2 and relative magnetic permeability 50. The wave impedance of such a medium is

(a) 5 W

(b) 376.6 W

(c) 1883 W

(d) 3776 W

Assertion   :   Two bulbs of same wattage, one having a carbon filament and the other having a metallic filament are connected in series. Metallic bulbs will glow more brightly than carbon filament bulb. 

Reason      : Carbon is a semiconductor.

(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.

Two coherent sources separated by distance d are radiating in phase having wavelength l. A detector moves in a big circle around the  two sources in the plane of the two sources. The angular position of n = 4 interference maxima is given as

(a)

(b)

(c)

(d)

Assertion   :   Separation of isotope is possible because of the difference in electron numbers of isotope.

Reason       : Isotope of an element can be separated by using a mass spectrometer.

(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 assertion is false but reason is true.