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प्रश्न
State factors on which the amount of heat radiated by a body depends.
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उत्तर
The amount of heat radiated by a body depends on:
- The absolute temperature of the body (T)
- The nature of the body – the material, nature of the surface - polished or not, etc.
- The surface area of the body (A)
- Time duration for which body emits radiation (t).
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संबंधित प्रश्न
The coolant in a chemical or a nuclear plant (i.e., the liquid used to prevent the different parts of a plant from getting too hot) should have high specific heat.
What property of water makes it an effective coolant?
Specific heat capacity of substance A is 3.8 J g-1K-1 whereas the specific heat capacity of substance B is 0.4 J g-1 K-1
(i) Which of the two is a good conductor of heat?
(ii) How is one led to the above conclusion?
(iii) If substances A and B are liquids then which one would be more useful in car radiators?
Heat supplied to a solid change it into liquid. What is this change in the phase called?
In an experiment to determine the specific heat capacity of a solid following operations were
made:
Mass of calorimeter + stirrer = x kg
Mass of water = y kg
Initial temperature of water t1℃
Mass of solid = z kg
Temperature of solid = t2 ℃
Temperature of mixture = t ℃
Specific heat capacity of calorimeter and water are c1 and c2 respectively. Express the specific
heat capacity c of the solid in terms of the above data.
State the effect of enhancement of green house effect.
What is carbon tax?
(i) State whether the specific heat capacity of a substance remains the same when its state changes from solid to liquid.
(ii) Give one example to support your answer.
What is the unit of heat capacity in CGS system?
A piece of iron of mass 2.0 kg has a heat capacity of 966 J K-1. Find its specific heat capacity in S.I unit.
Write two advantages of high specific heat capacity of water.
The farmers fill their fields with water in winter. Give reason.
1 kg of water freezes to form ice at 0°C. What amount of heat is withdrawn?
Derive an expression for finding out the specific heat capacity of a body (solid) from the readings of an experiment given below:
(i) Mass of empty calorimeter (with stirrer) = m1 gm
(ii) Mass of the metal piece = M gm
(iii) Mass of colorimeter and water = m2 gm
(iv) Initial temperature and water = t1°C
(v) Temperature of hot solid (metal piece) = t2 °C
(vi) Final temperature of the mixture = t°C
(vii) Specific heat of calorimeter = 0.4 J gm / °C
Solve the following problem.
What is the specific heat of metal if 50 cal of heat is needed to raise 6 kg of the metal from 20°C to 62 °C?
The molar specific heat of a gas at constant volume is 12307.69 J kg-1 K-1. If the ratio of the two specific heats is 1.65, calculate the difference between the two molar specific heats of gas.
From the options given below the specific heat of _______ is maximum.
The specific heat capacity of water is 1 cal/g °C.
Read this activity and answer the following questions.
- Take three spheres of iron, copper and lead. the lead of equal mass.
- Put all the three spheres in boiling water in the beaker for some time.
- Take the three spheres out of the water.
- All the spheres will be at a temperature 100 °C.
- Put them immediately on the thick slab of wax.
- Note, the depth that each of the sphere goes into the wax.
Questions:
- Which property is determined from this activity?
- Give name to that property.
- Explain the term principal of heat exchange with the help of this activity.
The cold object the hot object enclosed in one box of heat-resistant material.
- What changes will occur in the two objects when temperature flows from those objects?
- Which principle can show that the energy exchange takes place between two objects only when kept in isolated system?
Read the passage and answer the questions based on it.
If heat is exchanged between a hot and cold object, the temperature of the cold object goes on increasing due to gain of energy and the temperature of the hot object goes on decreasing due to loss of energy. The change in temperature continues till the temperatures of both objects attain the same value. In this process, the cold object gains heat energy and the hot object loses heat energy. If the system of both the objects is isolated from the environment by keeping it inside a heat-resistant box then no energy can flow from inside the box or come into the box. In this situation, we get the following principle.
Heat energy lost by the hot object = Heat energy gained by the cold object. This is called the ‘Principle of heat exchange’.
- Where does heat transfer take place?
- In such a situation which principle of heat do you perceive?
- How can this principle be explained in short?
- Measuring the property of which substance this principle is used?
_______ is defined as the amount of heat required to raise the temperature of 1kg of a substance by 1°C.
If 'Cp' and 'Cv' are molar specific heats of an ideal gas at constant pressure and volume respectively. If 'λ' is the ratio of two specific heats and 'R' is universal gas constant then 'Cp' is equal to ______.
Specific heat capacity C = ______.
J/Kg °C is the unit of specific heat capacity.
Two cylinders of equal height and radius are made of copper and aluminum. Which of them conducts heat faster?
When two kilocalories of heat are supplied to a system, the internal energy of the system increases by 5030 J and the work done by the gas against the external pressure is 3350 J. Calculate J, the mechanical equivalent of heat.
In the method of mixtures, a hot metal is dropped into cold water and the mixture reaches a final temperature. Which principle is used to find the specific heat of the metal?
