Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

An object is placed at a distance of f/2  from a convex lens. The image will be

(a) At one of the foci, virtual and double its size

(b) At 3f / 2, real and inverted

(c) At 2f, virtual and erect

(d) None of these

A wire of length 5 m and radius 1 mm has a resistance of 1 ohm. What length of the wire of the same material at the same temperature and of radius 2 mm will also have a resistance of 1 ohm

(a) 1.25 m

(b) 2.5 m

(c) 10 m

(d) 20 m

A bar magnet A of magnetic moment M_A is found to oscillate at a frequency twice that of magnet B of magnetic moment M_B when placed in a vibrating magneto-meter. We may say that

(a)

(b)

(c)

(d)

Ten grams of ⁵⁷Co kept in an open container beta-decays with a half-life of 270 days. The weight of the material inside the container after 540 days will be very nearly:

The energy consumed in 1 kilowatt electric heater in 30 seconds will be

(a) 6

(b) 4.99

(c) 9.8

(d) 3

A copper voltameter is connected in series with a heater coil of resistance 0.1 Ω. A steady current flows in the circuit for twenty minutes and mass of 0.99 g of copper is deposited at the cathode. If electrochemical equivalent of copper is 0.00033 gm/C, then heat generated in the coil is

(a) 750 J

(b) 650 J

(c) 350 J

(d) 250 J

Two independent parallel wires in which the current is flowing in the same direction. They will:

A very small magnet is placed in the magnetic meridian with its south pole pointing north. The null point is obtained 20cm away from the centre of the magnet. If the earth¢s magnetic field (horizontal component) at this point be 0.3 gauss, the magnetic moment of the magnet is:

Huygen’s principle of secondary wavelets may be used to

(a) Find the velocity of light in vacuum

(b) Explain the particle behaviour of light

(c) Find the new position of the wavefront

(d) Explain photoelectric effect

Light travels in a ________ path: