NEET Physics Calorimetry and Heat Transfer Online Test Set B

1. Assuming the sun to have a spherical outer surface of radius r, radiating like a black body at temperature t°C, the power received by a unit surface, (normal to the incident rays) at a distance R from the centre of the sun is

2. The tempertaure of equal masses of three different liquids A, B and C are 12°C, 19°C and 28°C respectively. Thetemperature when A and B are mixed is 16°C and when B and C are mixed is 23°C . The temperature when A and C are mixed is

3. A partition wall has two layers of different materials A and B in contact with each other. They have the same thickness but the thermal conductivity of layer A is twice that of layer B. At steady state the temperature difference across the layer B is 50 K, then the corresponding difference across the layer A is

4. The rectangular surface of area 8 cm × 4 cm of a black body at temperature 127°C emits energy E per second. If the length and breadth are reduced to half of the initial value and the temperature is raised to 327°C, the rate of emission of energy becomes

5. Two rods of same length and transfer a given amount of heat 12 second, when they are joined as shown in figure (i). But when they are joined as shown in figure (ii), then they will transfer same heat in same conditions in

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7. A sphere and a cube of same material and same volume are heated upto same temperature and allowed to cool in the same surroundings. The ratio of the amounts of radiations emitted will be

8. 12 identical rods made of same material are arranged in the form of a cube. The temperature of P and R are maintained at 90°C and 30°C respectively. Then the temperature of point V, when steady state is reached is

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10. A piece of ice falls from a height h so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice and all energy of ice gets converted into heat during its fall. The value of h is : [Latent heat of ice is 3.4 × 10⁵ J/kg and g = 10 N/kg]

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12. In the plot of temperature versus time showing changes in the state of ice on heating, which part represents constant temperature?

13. A tube shaped like a parallelogram is filled with liquid is kept in a vertical plane. Tube is heated at mid point of ad. The heat flows only by convection. Then

14. A slab of stone of area 0.36 m2 and thickness 0.1 m is exposed on the lower surface to steam at 100°C. A block of ice at 0°C rests on the upper surface of the slab. In one hour 4.8 kg of ice is melted. The thermal conductivity of slab is : (Given latent heat of fusion of ice = 3.36 × 10⁵ J kg^–1.) :

15. 300 gm of water at 25°C is added to 100 g of ice at 0°C. The final temperature of the mixture is

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17. Four identical rods of same material are joined end to end to form a square. If the temperature difference between the ends of a diagonal is 100°C, then the temperture difference between the ends of other diagonal will be

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19. The two ends of a metal rod are maintained at temperatures 100°C and 110°C. The rate of heat flow in the rod is found to be 4.0 J/s. If the ends are maintained at temperatures 200°C and 210°C, the rate of heat flow will be

20. On observing light from three different stars P, Q and R, it was found that intensity of violet colour is maximum in the spectrum of P, the intensity of green colour is maximum in the spectrum of R and the intensity of red colour is maximum in the spectrum of Q. If T_P, T_Q and T_R are the respective absolute temperature of P, Q and R, then it can be concluded from the above observations that

21. A kettle with 3 litre water at 27°C is heated by operating coil heater of power 2 kW. The heat is lost to the atmosphere at constant rate 130J/sec, when its lid is open. In how much time will water heated to 97°C with the lid open? (specific heat of water = 4.2 kJ/kg)

22. Ice starts forming in a lake with water at 0ºC when the atomspheric temperature is –10ºC. If the time taken for the first 1 cm of ice to be formed is 7 hours, then the time taken for the thickness of ice to change from 1 cm to 2 cm is

23. Five rods of same dimensions are arranged as shown in the figure. They have thermal conductivities K₁, K₂, K₃, K₄ and K₅. When points A and B are maintained at different temperatures, no heat flows through the central rod if

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