N molecules each of mass m of a gas A and 2N molecules each of mass 2m of gas B are contained in the same vessel which is maintained at temperature T. The mean square velocity of molecules of B type is v^{2} and the mean square rectangular component of the velocity of A type is denoted by ω^{2}. Then ω^{2}/v^{2} [1991]
10 gm of ice cubes at 0°C are released in a tumbler (water equivalent 55 g) at 40°C.Assuming that negligible heat is taken from the surroundings, the temperature of water in the tumbler becomes nearly (L = 80 cal/g) [1988]
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A centigrade and a Fahrenheit thermometer are dipped in boiling water. The water temperature is lowered until the Fahrenheit thermometer registers 140°. What is the fall in temperature as registered by the Centigrade thermometer ?
Thermal capacity of 40 g of aluminium (s = 0.2 cal /g K) is [1990]
Mercury thermometer can be used to measure temperature upto [1992]
If the temperature of the sun is doubled, the rate of energy received on earth will be increased by a factor of [1993]
A body cools from 50.0°C to 48°C in 5s. How long will it take to cool from 40.0°C to 39°C?Assume the temperature of surroundings to be 30.0°C and Newton's law of cooling to be valid.
A beaker full of hot water is kept in a room. If it cools from 80°C to 75°C in t_{1} minutes, from 75° C to 70°C in t_{2} minutes and from 70°C to 65°C in t_{3} minutes, then [1995]
A black body is at temperature of 500 K. It emits energy at rate which is proportional to [1997]
The radiant energy from the sun, incident normally at the surface of earth is 20 k cal/m^{2} min. What would have been the radiant energy, incident normally on the earth, if the sun had a temperature, twice of the present one? [1998]
If 1 g of steam is mixed with 1 g of ice, then the resultant temperature of the mixture is [1999]
The coefficient of linear expansions of brass and steel are α_{1} and α_{2} respectively. When we take a brass rod of length ℓ_{1} and a steel rod of length ℓ_{2} at 0ºC, then the difference in their lengths (ℓ_{2} – ℓ_{1}) will remain the same at all temperatures if [1995, 1999]
The presence of gravitational field is required for the heat transfer by [2000]
A black body has maximum wavelength λ_{m} at temperature 2000 K. Its corresponding wavelength at temperature 3000 K will be
A cylindrical rod having temperature T_{1} and T_{2} at its end. The rate of flow of heat is Q_{1} cal/sec.If all the linear dimensions are doubled keeping temperature constant, then the rate of flow of heat Q_{2} will be [2001]
Wien's law is concerned with [2002]
Radiation from which of the following sources, approximates black body radiation best? [2002]
Two rods of thermal conductivities K_{1} and K_{2}, crosssections A_{1} and A_{2 }and specific heats S_{1 }and S_{2} are of equal lengths. The temperatures of two ends of each rod are T_{1} and T_{2}. The rate of flow of heat at the steady state will be equal if [2002]
Consider a compound slab consisting of two different materials having equal thicknesses and thermal conductivities K and 2K, respectively.
The equivalent thermal conductivity of the slab is [2003]
If λ_{m} denotes the wavelength at which the radiative emission from a black body at a temperature T K is maximum, then [2004]
Which of the following circular rods (given radius r and length l), each made of the same material and whose ends are maintained at the same temperature will conduct most heat? [2005]
The temperature of in version of a thermocouple is 620^{0}C and the neutral temperature is 300^{0}C. What is the temperature of cold junction ? [2005]
A black body at 1227°C emits radiations with maximum intensity at a wavelength of 5000Å. If the temperature of the body is increased by 1000°C, the maximum intensity will be observed at
A black body is at 727° C. It emits energy at a rate which is proportional to [2007]
If the cold junction of a thermocouple is kept at 0°C and the hot junction is kept at T°C then the relation between neutral temperature (T_{n}) and temperature of inversion (T_{i}) is [2007]
Assuming the sun to have a sph erical 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 [2007] where σ is the Stefan’s constant.
On a new scale of temperature (which is linear) and called the W scale, the freezing and boiling points of water are 39° W and 239° W respectively. What will be the temperature on the new scale, corresponding to a temperature of 39° C on the Celsius scale? [2008]
An electric kettle takes 4A current at 220 V. How much time will it take to boil 1 kg of water from temperature 20° C? The temperature of boiling water is 100° C. [2008]
The two ends of a rod of length L and a uniform crosssectional area A are kept at two temperatures T_{1} and T_{2} (T_{1} > T_{2}). The rate of heat transfer, through the rod in a steady state is given by: [2009]
A black body at 227°C radiates heat at the r ate of 7 cals/cm^{2}s. At a temperature of 727°C, the rate of heat radiated in the same units will be:
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102 videos411 docs121 tests
