The coefficient of linear expansion of brass and steel rods are \(\alpha_1\) and \(\alpha_2\). Lengths of brass and steel rods are \(L_1\) and \(L_2\) respectively. If \((L_2-L_1)\) remains the same at all temperatures, which one of the following relations holds good?
1. \(\alpha_1L_2^2=\alpha_2L_1^2\)
2. \(\alpha_1^2L_2=\alpha_2^2L_1\)
3. \(\alpha_1L_1=\alpha_2L_2\)
4. \(\alpha_1L_2=\alpha_2L_1\)
On observing light from three different stars \(P\), \(Q\), and \(R\), it was found that the intensity of the violet colour is maximum in the spectrum of \(P\), the intensity of the green colour is maximum in the spectrum of \(R\) and the intensity of the red colour is maximum in the spectrum of \(Q\). If \(T_P\), \(T_Q\), and \(T_R\) are the respective absolute temperatures of \(P\), \(Q\), and \(R\), then it can be concluded from the above observations that:
1. \(T_P>T_Q>T_R\)
2. \(T_P>T_R>T_Q\)
3. \(T_P<T_R<T_Q\)
4. \(T_P<T_Q<T_R\)
A black body at \(227^{\circ}~\mathrm{C}\) radiates heat at the rate of \(7~ \mathrm{cal-cm^{-2}s^{-1}}\). At a temperature of \(727^{\circ}~\mathrm{C}\), the rate of heat radiated in the same units will be:
1. \(60\)
2. \(50\)
3. \(112\)
4. \(80\)
On a new scale of temperature, which is linear and called the \(\mathrm{W}\) scale, the freezing and boiling points of water are \(39^\circ ~\mathrm{W}\)and \(239^\circ ~\mathrm{W}\) respectively. What will be the temperature on the new scale corresponding to a temperature of \(39^\circ ~\mathrm{C}\) on the Celsius scale?
1. \(78^\circ ~\mathrm{C}\)
2. \(117^\circ ~\mathrm{W}\)
3. \(200^\circ ~\mathrm{W}\)
4. \(139^\circ ~\mathrm{W}\)
Two rods \(A\) and \(B\) of different materials are welded together as shown in the figure. Their thermal conductivities are \(K_1\) and \(K_2.\) The thermal conductivity of the composite rod will be:
1. | \(\frac{3(K_1+K_2)}{2}\) | 2. | \(K_1+K_2\) |
3. | \(2(K_1+K_2)\) | 4. | \(\frac{(K_1+K_2)}{2}\) |
A black body at \(200\) K is found to emit maximum energy at a wavelength of \(14\) \(\mu \)m. When its temperature is raised to \(1000\) K, the wavelength at which maximum energy is emitted will be:
1. | \(14\) \(\mu \)m | 2. | \(70\) \(\mu \)m |
3. | \(2.8\) \(\mu \)m | 4. | \(2.8\) nm |
The triple points of neon and carbon dioxide are \(24.57\) K and \(216.55\) K respectively. The value of these temperatures on Fahrenheit scales will be:
1. | \(-415.44^\circ ~\mathrm{F} ,~-69.88^\circ ~\mathrm{F}\) |
2. | \(-248.58^\circ ~\mathrm{F} ,~-56.60^\circ~ \mathrm{F}\) |
3. | \(315.44^\circ ~\mathrm{F} ,~-69.88^\circ ~\mathrm{F}\) |
4. | \(415.44^\circ ~\mathrm{F} ,~-79.88^\circ~ \mathrm{F}\) |
A brass wire \(1.8\) m long at \(27\) °C is held taut with a little tension between two rigid supports. If the wire is cooled to a temperature of\(-39\) °C, what is the tension created in a wire with a diameter of \(2.0\) mm? (coefficient of linear expansion of brass \(=2.0 \times10^{-5}\) K–1, Young's modulus of brass\(=0.91 \times10^{11}\) Pa)
1. \(3.8 \times 10^3\) N
2. \(3.8 \times 10^2\) N
3. \(2.9 \times 10^{-2}\) N
4. \(2.9 \times 10^{2}\) N
The coefficient of area expansion \(\beta\) of a rectangular sheet of a solid in terms of the coefficient of linear expansion \(\alpha\) is:
1. \(2\alpha\)
2. \(\alpha\)
3. \(3\alpha\)
4. \(\alpha^2\)
When \(0.15\) kg of ice at \(0^\circ \text{C}\) is mixed with \(0.30\) kg of water at \(50^\circ \text{C}\) in a container, the resulting temperature is \(6.7^\circ \text{C}.\)
The heat of fusion of ice is: (\(S_{\text{water}}=4186\) J kg–1 K–1)
1. \( 3.43 \times 10^4\) Jkg–1
2. \( 3.34 \times 10^4\) Jkg–1
3. \( 3.34 \times 10^5\) Jkg–1
4. \(4.34 \times 10^5\) Jkg–1