Wave Optics — Physics STD 12 Science — Question

The capacitive reactance in an AC circuit is.

A beam of light of wavelength 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is

(a) 1.2 mm

(b) 1.2 cm

(c) 2.4 cm

(d) 2.4 mm

A block A kept on an inclined surface just begins to slide if the inclination is 30°. The block is replaced by another block B and it is found that it just begins to slide if the inclination is 40°:

1. Mass of A > mass of B.
2. Mass of A < mass of B.
3. Mass of A = mass of B.
4. All the three are possible.

If   and  are the number of electrons and holes in a semiconductor heavily doped with phosphorus, then

(a)

(b)

(c)

(d)

As per this diagram a point charge +q is placed at the origin O. Work done in taking another point charge -Q  from the point A [co-ordinates (0, a) ] to another point B [co-ordinates (a, 0)] along the straight path AB is

(a) Zero

(b)

(c)

(d)

A particle of mass 'm' and charge 'q' enters in an uniform magnetic field B perpendicularly. The radius of its path will be :

The mass and energy equivalent to 1 a.m.u. respectively

(a) 1.67	(b) 1.67
(c) 1.67	(d) 1.67

A galvanometer coil of resistance 50 W, show full deflection of 100 μA. The shunt resistance to be added to the galvanometer, to work as an ammeter of range 10 mA is

(a) 5 W in parallel

(b) 0.5 W in series

(c) 5 W in series

(d) 0.5 W in parallel

Energy is stored in a capacitor in the form of:

Assertion  :   When charges are shared between any two bodies, no charge is really lost, but some loss of energy does occur.

Reason      : Some energy disappears in the form of heat, sparking etc.

(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.