Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : A body that is a good radiator is also a good absorber of radiation at a given wavelength.
Reason : According to Kirchhoff's law the absorptivity of a body is equal to its emissivity at a given wavelength.
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : Temperatures near the sea coast are moderate.
Reason : Water has a high thermal conductivity.
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Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : Bodies radiate heat at all temperatures.
Reason : Rate of radiation of heat is proportional to the fourth power of absolute temperature.
Assertion :The equivalent thermal conductivity of two plates of same thickness in contact is less than the smaller value of thermal conductivity
Reason: For two plates of equal thickness in contact the equivalent thermal conductivity is given by:
1/K=1/K1+1/K2
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : If the temperature of a star is doubled then the rate of loss of heat from it becomes 16 times.
Reason : Specific heat varies with temperature.
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : Blue star is at high temperature than red star.
Reason : Wein's displacement law states that T∝(1/λm).
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : A brass tumbler feels much colder than a wooden tray on a chilly day.
Reason : The thermal conductivity of brass is less than that of wood.
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : For higher temperature, the peak emission wavelength of a black body shifts to lower wavelengths.
Reason : Peak emission wavelength of a blackbody is proportional to the fourth power of temperature.
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : It is hotter over the top of a fire than at the same distance on the sides.
Reason : Air surrounding the fire conducts more heat upwards.
Read the assertion and reason carefully to mark the correct option out of the options given below:
Assertion : Woolen clothes keep the body warm in winter.
Reason : Air is a bad conductor of heat.
9 docs|1272 tests
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9 docs|1272 tests
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