Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A radioactive sample has  active atoms at t = 0. If the rate of disintegration at any time is R and the number of atoms is N, then the ratio R/N varies with time as

(a)

(b)

(c)

(d)

What is the equivalent resistance between the points A and B of the network

(a)

(b) 8 W

(c) 6 W

(d)

The minimum distance between an object and its real image formed by a convex lens is

(a) 1.5 f

(b) 2 f

(c) 2.5 f

(d) 4 f

Current I is flowing in a wire of infinite length. Magnetic field is B at a perpendicular distance r from the wire. The correct relation is:

Which of the following does not fit into a group:

A coil of insulating wire is connected to battery. If it is moved towards a galvanometer then its point gets deflected because.

For a medium, refractive indices for violet, red and yellow are 1.62, 1.52 and 1.55 respectively, then dispersive power of medium will be

(a) 0.65

(b) 0.22

(c) 0.18

(d) 0.02

Length of a hollow tube is 5m, it’s outer diameter is 10 cm and thickness of it’s wall is 5 mm. If resistivity of the material of the tube is 1.7 ×  W × m then resistance of tube will be

(a) 5.6 × 10–5 W

(b) 2 × 10–5 W

(c) 4 × 10–5 W

(d) None of these

Which of the following shown particle nature of light

(a) Refraction

(b) Interference

(c) Polarization

(d) Photoelectric effect

A capacitor of capacity C is connected with a battery of potential V in parallel. The distance between its plates is reduced to half at once, assuming that the charge remains the same. Then to charge the capacitance upto the potential V again, the energy given by the battery will be

(a)

(b)

(c)

(d)