The diagram shows a bimetallic strip used as a thermostat in a circuit. Copper expands more than Invar for the same temperature rise.

What will be switched on when the bimetallic strip becomes hot?

1.	bell only	2.	lamp and bell only
3.	motor and bell only	4.	lamp, bell, and motor

A piece of iron is heated in a flame. If it becomes dull red first, then becomes reddish yellow, and finally turns to white hot, the correct explanation for the above observation is possible by using:

In an experiment on the specific heat of a metal, a 0.20 kg block of the metal at \(150^{\circ}\mathrm{C}\) is dropped in a copper calorimeter (of water equivalent of 0.025 kg) containing 150 \(c m^{3}\) of water at \(27^{\circ}\mathrm{C}\). The final temperature is \(40^{\circ}\mathrm{C}\). The specific heat of the metal will be: (Heat   losses   to   the   surroundings   are   negligible)
1. \(0 . 40  ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
2. \(0 . 43  ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
3. \(0 . 54 ~ \text{Jg}^{- 1} \text{K}^{- 1}\)
4. \(0 . 61 ~ \text{Jg}^{- 1} \text{K}^{- 1}\)

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

A large steel wheel is to be fitted onto a shaft of the same material. At 27 °C, the outer diameter of the shaft is 8.70 cm and the wheel's central hole has a diameter of 8.69 cm. The shaft is cooled using ‘dry ice’. At what temperature of the shaft does the wheel slip on the shaft?
(Assume the coefficient of linear expansion of the steel to be constant over the required temperature range  and \(\alpha\) steel = \(1.20 \times 10^{-5} K^{-1}\))
1. 68°C
2. -70°C
3.  -69°C
4. -67°C

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: 

When a uniform rod is heated, which of its following properties will increase as a result of it?
1. mass
2. weight
3. center of mass
4. moment of inertia

Three stars \(A,\) \(B,\) and \(C\) have surface temperatures \(T_A,~T_B\)and \(T_C\) respectively. Star \(A\) appears bluish, star \(B\) appears reddish and star \(C\) yellowish. Hence,

A slab of stone with an area \(0.36~\text{m}^{2}\)${\mathrm{}}^{}$ and thickness of \(0.1~\text{m}\) is exposed on the lower surface to steam at \(100​​^{\circ}\mathrm{C}\)$$. A block of ice at \(0^{\circ}\mathrm{C}\) rests on the upper surface of the slab. In one hour \(4.8~\text{kg}\) of ice is melted. The thermal conductivity of the slab will be: (Given latent heat of fusion of ice \(= 3.36\times10^{5}~\text{JKg}^{-1}\)${\mathrm{}}^{}$)
1. \(1.29~\text{J/m/s/}^{\circ}\text{C}\)
2. \(2.05~\text{J/m/s/}^{\circ}\text{C}\)
3. \(1.02~\text{J/m/s/}^{\circ}\text{C}\)
4. \(1.24~\text{J/m/s/}^{\circ}\text{C}\)