A black surface absorbs more heat radiations as compared to a white or a reflecting surface under identical conditions. List two solar devices which make use of this property in their design.
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For the process to occur under adiabatic conditions, the correct conditions is (i) ΔT = 0 (ii) Δp = 0 (iii) q = 0 (iv) w = 0
The correct conditions is q = 0. So option (iii) is correct.
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An echo returned in 3 s. What is the distance of the reflecting surface from the source
Speed of sound, v = 342 m s−1 Echo returns in time, t = 3 s Distance travelled by sound = v × t = 342 × 3 = 1026 m In the...
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An echo is returned in 6 seconds. What is the distance of reflecting surface from source? [Given that speed of sound is 342 m/s.]
Given, Time in which echo returned, t = 6 s, Speed of sound, v = 342 m/s Distance = Speed × Time = 342 × 6 = 2052m As this distance is twice the...
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The concave reflecting surface of a torch got rusted. What effect would this have on the beam of light from the torch?
The beam of light will be diffused with lower intensity
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A heat engine absorbs heat Q1 at temperature T1 and heat Q2 at temperature T2.
(d) : It does not violate first law of thermodynamics but violates second law of thermodynamics.
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A spinning wheel is brought in contact with an identical wheel spinning at identical speed.
The correct answer is: (a), (c) (a), kinetic (c) mechanical
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(a) Why are infra-red radiations referred to as heat waves?
(a) Infrared waves are produced by hot bodies and molecules, so are referred to as heat waves. (i) Em wave having short wavelength than infrared waves are visible, UV, γ-rays and...
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Under what conditions is the heat absorbed by a system is equal to the work done by the system?
When ∆U=0 i.e, for isothermal process q = w
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If a system absorbs 500 cal of heat at the same time does 400J of work, find the change in internal energy of the system.
ΔU = q + w (1 Calorie =4.2 J) ΔU = 2100+(-400) = 1700J
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A square is divided into 9 identical smaller squares. Six identical balls are to be placed in these smaller
(d) Total number of ways in which 9 balls occupy any of the 6 squares = 9C6 = 84 Number of ways in which one row is not filled = 3 ∴...
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