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Why is the energy of thermal radiation less than that of visible
asked
Mar 19, 2022
in
11th Physics
marks1
chapter11
#sub
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0
answers
Two rods A and B are of equal length. Each rod has its ends at temperature T1 and T2 (T1 > T2). What is the condition that will ensure equal rates of flow through the rods A and
asked
Mar 19, 2022
in
11th Physics
marks1
chapter11
#sub
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A Sphere is at a temperature of 6oo k. Its cooling rate is R in an external environment of 200k. If temperature falls to 400k. What is the cooling rate R1 in terms of
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Mar 19, 2022
in
11th Physics
marks1
chapter11
#sub
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If the temperature of the sun is doubled, the rate of energy received on each will increases by what
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Mar 19, 2022
in
11th Physics
marks1
chapter11
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How do you explain the emission of long - wavelength by the object at low
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Mar 19, 2022
in
11th Physics
marks1
chapter11
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If the radiation from the moon gives maxima at `λ = 4700 A^o and λ = 14xx10^(-6)m`. What conclusion can be drawn from the above
asked
Mar 19, 2022
in
11th Physics
marks2
chapter11
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Differentiate between conduction, convection and
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Mar 19, 2022
in
11th Physics
marks2
chapter11
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The tile floor feels colder than the wooden floor even though both floor materials are at same temperature.
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Mar 19, 2022
in
11th Physics
marks2
chapter11
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A spherical black body of radius 12cm radiates 450w power at 500k. If the radius were halved and the temperature doubled, what would be the power
asked
Mar 19, 2022
in
11th Physics
marks2
chapter11
#sub
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A cylinder of radius R made of a material of thermal conductivity K1 is surrounded by a cylindrical shell of inner radius R and other radius 2R made of material of thermal conductivity K2. The 2 ends of combined system are maintained at two different temperatures. There is no loss of heat across the clinical surface and the system is in steady state calculate the effective thermal conductivity of the
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Mar 19, 2022
in
11th Physics
marks2
chapter11
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A room has a 4m x 4m x10cm concrete roof `(K_1 = 1.26w|m|'^oC)`. At some instant, the temperature outside is `46^oc` and radius `32^oc`. 1) Calculate amount of heat flowing per second into the room through the roof. 2) If bricks `(K_2 – 0.56w |m|'^oc)` of thickness 7.5cm are laid down on roof, calculate the new rate of heat flow under the same temperature
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Mar 19, 2022
in
11th Physics
marks2
chapter11
#sub
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A bar of copper of length 75cm and a bar of length 125cm are joined end to end. Both are of circular cross – section with diameters 2cm. The free ends of copper and steel are maintained at `100^oc and 0^oc` respectively. The surfaces of the bars are thermally insulated. What is the temperature of copper – steel junction? Thermal conductivity of copper `= 9.2xx10^(-2)k cal |m|'^oc|s` and that of steel is `1.1xx10^(-2) k
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Mar 19, 2022
in
11th Physics
marks2
chapter11
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If air is a bad conductor of heat, why do we not feel warm without
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Mar 19, 2022
in
11th Physics
marks1
chapter11
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A body with large reflectivity is a poor emitter
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Mar 19, 2022
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11th Physics
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chapter11
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Animals curl into a ball, when they feel very
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Mar 19, 2022
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11th Physics
marks1
chapter11
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Why is it hotter at the same distance over the top of the fire than in front of
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Mar 19, 2022
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11th Physics
marks2
chapter11
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A metal rod of length 20cm and diameter 2cm is covered with a non-conducting substance. One of it ends is maintained at `100^oc` while the other is at `0^oc`. It is found that 25g of ice melts in 5 min calculate coefficient of thermal conductivity of
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Mar 19, 2022
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11th Physics
marks2
chapter11
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Calculate the temperature in Kelvin at which a perfectly black body radiates at the rate of 5.67
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Mar 19, 2022
in
11th Physics
marks2
chapter11
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How do you derive Newton’s law of cooling from Stefan’s
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Mar 19, 2022
in
11th Physics
marks3
chapter11
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Define the terms reflectance, absorptance and transmittance. How are they
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Mar 19, 2022
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11th Physics
marks3
chapter11
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