21.

The figure below shows currents in a part of an electric circuit. The current I is

A) 1.7amp

B) 3.7amp

C) 1.3amp

D) 1amp

22.

The Young's modulus of a perfectly rigid body is

A) Unity

B) Zero

C) Infinity

D) Some finite non zero constant

23.

A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass the same which one of the following will not be affected?

A) Angular velocity

B) Angular momentum

C) Moment of inertia

D) Rotational kinetic energy

24.

A mass of 0.5 kg moving with a speed of 1.5 m/ s on a horizontal smooth surface, collides with a nearly weightless spring of force constant k: 50N/m. The maximum compression of the spring would be

A) 0.5m

B) 0.15m

C) 0.12m

D) 1.5m

25.

Consider a pair of insulating blocks with thermal resistances R_{1} and R_{2} as shown in the figure. The temperature θ at the boundary between the two blocks is

A) $\frac{\theta_{1}\theta_{2}\sqrt{R_{1}R_{2}}}{(\theta_{1}+\theta_{2})(R_{1}+R_{2})}$

B) $\frac{\theta_{1}R_{1}+ \theta_{2}R_{2}}{(R_{1}+R_{2})}$

C) $\frac{\left[\left(\theta_{1}+ \theta_{2}\right) R_{1}R_{2}\right]}{\left(R_1^2+ R_2^2\right)}$

D) $\frac{\left(\theta_{1}R_{2}+ \theta_{2}R_{1}\right)}{R_{1}+ R_{2}}$

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