Water is heated from 0° C to 10° C, then its volume

• does not change

• decreases

• first decreases and then increases

• increases

The efficiency of a Carnot engine which operates between the two temperatures T₁ = 500 K and T₂ = 300 K is

• 75 %

• 50 %

• 40 %

• 25 %

The ratio of hydraulic stress to the corresponding strain is known as

• Young's modulus

• compressibility

• Rigidity modulus

• Bulk's modulus

A stretched string is vibrating in the second overtone, then the number of nodes and anti-nodes between the ends of the string are respectively

• 3 and 4

• 4 and 3

• 2 and 3

• 3 and 2

When two tuning forks A and B are sounded together, 4 beats per second are heard. The frequency of the fork B is 348 Hz. When one of the prongs of the fork A is filled and sounded with B, the beat frequency increases, then the frequency of the fork A is

• 379 Hz

• 380 Hz

• 389 Hz

• 388 Hz

If there is no torsion in the suspension thread, then the time period of a magnet executing SHM is

• $\mathrm{T} = 2\mathrm{\pi } \sqrt{\frac{\mathrm{I}}{\mathrm{MB}}}$

• $\mathrm{T} = \frac{1}{2\mathrm{\pi }} \sqrt{\frac{\mathrm{MB}}{\mathrm{I}}}$

• $\mathrm{T} = 2\mathrm{\pi } \sqrt{\frac{\mathrm{MB}}{\mathrm{I}}}$

• $\mathrm{T} = \frac{1}{2\mathrm{\pi }} \sqrt{\frac{\mathrm{I}}{\mathrm{MB}}}$

The circuit has two oppositely connected ideal diodes in parallel. What is the current flowing in the circuit ?

• 2.31 A

• 1.71 A

• 1.33 A

• 2.0 A

The angle between the dipole moment and electric field at any point on the equatorial plane is

• 180°

• 0°

• 45°

• 90°

Pick out the statement which is incorrect ?

• A negative test charge experiences a force opposite to the direction of the field

• The tangent drawn to a line of force represents the direction of electric field

• Field lines never intersect

• The electric field lines forms closed loop

20.

Two spheres carrying charges + 6 µC and + 9 µC, separated by a distance d, experiences a force of repulsion F. When a charge of −3 μC is given to both the spheres and kept at the same distance as before, the new force of repulsion is

• $\frac{\mathrm{F}}{3}$

• F

• $\frac{\mathrm{F}}{9}$

• 3F