11.

Eight equal drops of water are falling through air with a steady velocity of 10 cm s^-1. If the drops combine to form a single drop big in size, then the terminal velocity of this big drop is

• 40 cms^-1

• 10 cms^-1

• 30 cms^-1

• 80 cms^-1

Two capillary tubes of different diameters are dipped in water. The rise of water is

• the same in both tubes

• greater in the tube of larger diameter

• greater in the tube of smaller diameter

• independent of the diameter of the tube

A perfect gas at 27°C is heated at constant pressure so as to double its volume. The increase in temperature of the gas will be

• 600°C

• 327°C

• 54°C

• 300°C

Three identical rods A, B and C are placed end to end. A temperature difference is maintained between the free ends of A and C. The thermal conductivity of B is thrice that of C and half ofthat of A. The effective thermal conductivity of the system will be (K_A is the thermal conductivity of rod A)

• $\frac{1}{3} {\mathrm{K}}_{\mathrm{A}}$

• 3 K_A

• 2 K_A

• $\frac{2}{3} {\mathrm{K}}_{\mathrm{A}}$

The quantities of heat required to raise the temperatures of two copperspheres of radii r₁ and r₂ (r₁ = 1.51 r₂) through 1 K are in the ratio of

• $\frac{27}{8}$

• $\frac{9}{4}$

• $\frac{3}{2}$

• 1

Which one of the following is v-T graph for perfectly black body ? v_m is the frequency of radiation with maximum intensity. T is the absolute temperature.

• A

• B

• C

• D

A particle executing a simple harmonic motion has a period of 6 s. The time taken by the particle to move from the mean position to half the amplitude, starting from the mean position is

• $\frac{3}{2} \mathrm{s}$

• $\frac{1}{2} \mathrm{s}$

• $\frac{3}{4} \mathrm{s}$

• $\frac{1}{4} \mathrm{s}$

The equation of a wave is given by $\mathrm{y} = 10 \sin \left(\frac{2\mathrm{\pi }}{45} \mathrm{t} + \mathrm{\alpha }\right)$. If the displacement is 5 cm at t = 0, then the total phase at t =7.5 s is

• $\frac{\mathrm{\pi }}{3}$

• $\frac{\mathrm{\pi }}{2}$

• $\frac{\mathrm{\pi }}{6}$

• $\mathrm{\pi }$

Two tuning forks A and B, produce notes of frequencies 258 Hz and 262 Hz. An unknown note sounded with A produces certain beats. When the same note is sounded with B, the beat frequency gets doubled. The unknown frequency is

• 250 Hz

• 252 Hz

• 254 Hz

• 256 Hz

A wire under tension vibrates with a fundamental frequency of 600 Hz. If the length of the wire is doubled, the radius is halved and the wire is made to vibrate under one-ninth the tension. Then the fundamental frequency will become

• 200 Hz

• 300 Hz

• 600 Hz

• 400 Hz