Recent questions in 11th Physics

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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 by varun (6.7k points)

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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

asked Mar 19, 2022 in 11th Physics by varun (6.7k points)

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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

asked Mar 19, 2022 in 11th Physics by varun (6.7k points)

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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

asked Mar 19, 2022 in 11th Physics by varun (6.7k points)

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If air is a bad conductor of heat, why do we not feel warm without

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A body with large reflectivity is a poor emitter

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Animals curl into a ball, when they feel very

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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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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

asked Mar 19, 2022 in 11th Physics by varun (6.7k points)

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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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How do you derive Newton’s law of cooling from Stefan’s

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Define the terms reflectance, absorptance and transmittance. How are they

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Discuss briefly energy distribution of a black body radiation. Hence deduce wien’s displacement

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Can you design heat energy of 100%

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Does the working of an electric refrigerator defy second law of

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A Carnot engine absorb `6×10^5` cal at `227^oc` calculate work done per cycle by the engine if it sink is at

asked Mar 19, 2022 in 11th Physics by varun (6.7k points)

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How does second law of thermodynamics explain expansion of

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Calculate difference in efficiency of a Carnot energy working between:-1) 400K and 350K2) 350K and

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Derive an expression for the work done during isothermal

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Briefly describe a Carnot cycle and derive an expression for the efficiency of Carnot

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