EASY
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The specific latent heat of vaporization of water is____

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Important Questions on Heat Transfer

MEDIUM

Due to cold weather, a 1 m water pipe of cross-sectional area 1 cm2 is filled with ice at -10 °C. Resistive heating is used to melt the ice. Current of 0.5 A is passed through 4  resistance. Assuming that all the heat produced is used for melting, what is the minimum time required?

(Given latent heat of fusion for water/ice=3.33×105 J kg-1, specific heat of ice =2×103 J kg-1 °C-1 and density of ice =103 kg m-3 )

MEDIUM

Two different liquids of same mass are kept in two identical vessel, which are placed in a freezer that extracts heat from them at the same rate causing each liquid to transform into a solid. The schematic figure below shows the temperaure T vs time t plot for the two materials. We denote the specific heat in the liquid states to be CL1 and CL2 for materials 1 and 2 respectively, and latent heats of fusion U1 and U2 respectively.

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Choose the correct option.

HARD
A 10.0 W electrical heater is used to heat a container filled with 0.5 kg of water. It is found that the temperature of the water and the container rise by 3 K in 15 minutes. The container is then emptied, dried, and filled with 2 kg of an oil. It is now observed that the same heater raises the temperature of the container-oil system by 2 K in 20 minutes. Assuming no other heat losses in any of the processes, the specific heat capacity of the oil is
EASY

When heat is supplied at equal rates to three substances A, B, C and their temperatures are plotted against time, the following graph is obtained. Which material among A, B and C has the least heat capacity?

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MEDIUM

A horizontal fire hose with a nozzle of cross-sectional area 521×10-3 m2 delivers a cubic metre of water in 10 s. What will be the maximum possible increase in the temperature of water while it hits a rigid wall (neglecting the effect of gravity)?

HARD
A current carrying wire heats a metal rod. The wire provides a constant power P to the rod. The metal rod is enclosed in an insulated container. It is observed that the temperature T in the metal rod changes with time t as: Tt=T01+βt14
, where β is a constant with appropriate dimension while T0 is a constant with dimension of temperature. The heat capacity of the metal is:
MEDIUM

Two different liquids of same mass are kept in two identical vessels, which are placed in a freezer that extracts heat from them at the same rate causing each liquid to transform into a solid. The schematic figure below shows the temperature T vs time t plot for the two materials. We denote the specific heat of materials in the liquid (solid) states to be CL1CS1 and CL2CS2 respectively.

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EASY
Amount of heat required to convert 10 g of ice to water at 20 is
EASY

Heat given to a body which raises its temperature by 1oC is

EASY
Water falls from a height of 500 m. What is the rise in temperature of water at the bottom if whole energy is used up in heating water?
EASY
 A gaseous mixture contains an equal number of hydrogen and nitrogen molecules. Specific heat measurements on this mixture at a temperature below 150 K would indicate the value of the ratio of specific heats for the mixture as 
EASY
If the ratio of densities of two substances is 5 :6 and that of the specific heats is 3 :5. Then the ratio between heat capacities per unit volume is
EASY
Two bodies of specific heat capacities S1 and S2 have the same heat capacities. They are combined to form a single composite body. The specific heat capacity of the composite body is
EASY
Heat capacity of a substance is infinite. It means
EASY

Write the value of Latent heat of fusion of ice with units.

MEDIUM

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Identify the part representing latent heat of vaporization in the temperature vs heat graph for melting of ice.

MEDIUM

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Identify the part representing latent heat of fusion in the temperature vs heat graph for melting of ice.

EASY
Water falls from a height of 500 m. What is the rise in temperature of water at the bottom if whole energy is used up in heating water?
MEDIUM
The ratio of thermal capacities of two spheres A and B, if their diameters are in the ratio 1:2, densities in the ratio 2:1, and the specific heat in the ratio of1:3, will be
MEDIUM
Energy is provided to a liquid at its boiling point at a rate of P joules per second. The rate at which mass is boiling away is μ kg per second. What is the specific latent heat of vaporisation of the liquid?