UPSC 2001 › Science & Technology › Physics

Two wires have their lengths, diameters and resistivities, all in the ratio of 1 : 2. If the resistance of the thinner wire is 10 ohms, the resistance of the thicker wire is

Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water.

Reason (R): The light coming from the stick undergoes scattering from water molecules giving the stick a short and bent appearance.

Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece.

Reason (R): The density of copper is more than that of glass.

Assertion (A): The boiling point of water decreases as the altitude increases.

Reason (R): The atmospheric pressure increases with altitude.

When light waves pass from air to glass, the variables affected are

When water is heated from 0 °C to 10 °C, its volume

Match List I with List II

and select the correct answer using the codes given below the Lists:

List I (Characteristic) I. Zero mass II. Fractional charge III. Fractional spin IV. Integral spin

List II (Particle) A) Positron B) Neutrino C) Quark D) Phonon

The mass of a body on Earth is 100 kg (acceleration due to gravity, gₑ = 10 m/s²). If acceleration due to gravity on the Moon = gₑ/6, then the mass of the body on the moon is

Consider the following statements: A simple pendulum is set into oscillation. Then I. The acceleration is zero when the bob passes through the mean position. II. In each cycle the bob attains a given velocity twice. III. Both acceleration and velocity of the bob are zero when it reaches its extreme position during its oscillation. IV. The amplitude of oscillation of the simple pendulum decreases with time.

Which of these statements are correct?