| 1. | \(26.8\%\) | 2. | \(20\%\) |
| 3. | \(6.25\%\) | 4. | \(12.5\%\) |
At what temperature will the \(\text{rms}\) speed of oxygen molecules become just sufficient for escaping from the earth's atmosphere?
(Given: Mass of oxygen molecule \((m)= 2.76\times 10^{-26}~\text{kg}\), Boltzmann's constant \(k_B= 1.38\times10^{-23}~\text{J K}^{-1}\))
1. \(2.508\times 10^{4}~\text{K}\)
2. \(8.360\times 10^{4}~\text{K}\)
3. \(5.016\times 10^{4}~\text{K}\)
4. \(1.254\times 10^{4}~\text{K}\)
| 1. | \(7.14\) A | 2. | \(5.98\) A |
| 3. | \(14.76\) A | 4. | \(11.32\) A |
An inductor of \(20~\text{mH}\), a capacitor of \(100~\mu \text{F}\), and a resistor of \(50~\Omega\) are connected in series across a source of emf, \(V=10 \sin (314 t)\). What is the power loss in this circuit?
1. \( 0.79 ~\text{W} \)
2. \( 0.43 ~\text{W} \)
3. \( 2.74 ~\text{W} \)
4. \( 1.13 ~\text{W}\)
A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from:
| 1. | the current source |
| 2. | the magnetic field |
| 3. | the lattice structure of the material of the rod |
| 4. | the induced electric field due to the changing magnetic field. |
The current sensitivity of a moving coil galvanometer is \(5~\text{div/mA}\) and its voltage sensitivity (angular deflection per unit voltage applied) is \(20~\text{div/V}.\) The resistance of the galvanometer is:
1. \(40~\Omega\)
2. \(25~\Omega\)
3. \(250~\Omega\)
4. \(500~\Omega\)
If the mass of the sun were ten times smaller and the universal gravitational constant were ten times larger in magnitude, which of the following statements would not be correct?
| 1. | Raindrops would drop faster. |
| 2. | Walking on the ground would become more difficult. |
| 3. | Time period of a simple pendulum on the earth would decrease. |
| 4. | Acceleration due to gravity \((g)\) on earth would not change. |
A solid sphere is in rolling motion. In rolling motion, a body possesses translational kinetic energy (Kt) as well as rotational kinetic energy (Kr) simultaneously. The ratio Kt : (Kt + Kr) for the sphere will be:
1. 7:10
2. 5:7
3. 10:7
4. 2:5
The kinetic energies of a planet in an elliptical orbit around the Sun, at positions \(A,B~\text{and}~C\) are \(K_A, K_B~\text{and}~K_C\) respectively. \(AC\) is the major axis and \(SB\) is perpendicular to \(AC\) at the position of the Sun \(S\), as shown in the figure. Then:
1. \(K_A <K_B< K_C\)
2. \(K_A >K_B> K_C\)
3. \(K_B <K_A< K_C\)
4. \(K_B >K_A> K_C\)
A solid sphere is rotating freely about its axis of symmetry in free space. The radius of the sphere is increased keeping its mass the same. Which of the following physical quantities would remain constant for the sphere?
| 1. | angular velocity |
| 2. | moment of inertia |
| 3. | rotational kinetic energy |
| 4. | angular momentum |