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प्रश्न
The substance which allows heat radiations to pass through is _______.
(A) iron
(B) water vapour
(C) wood
(D) dry air
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उत्तर
dry air
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संबंधित प्रश्न
Define emissive power and coefficient of emmision of a body.
The dimensions of emissive power are ______.
A pinhole is made in a hollow sphere of radius 5 cm whose inner wall is at temperature 727oC. Find the power radiated per unit area. [Stefan’s constant σ = 5.7 x 10-8 J/m2 s K4 , emissivity (e) = 0.2]
A metal ball cools from 64 °C to 50 °C in 10 minutes and to 42 °C in next 10 minutes. The ratio of rates of fall of temperature during the two intervals is _______.
A body cools from 62°C to 54°C in 10 minutes and to 48°C in the next 10 minutes. Find the temperature of the surroundings.
The kinetic energy per molecule of a gs at temperature T is ________.
(a) `(3/2)RT`
(b) `(3/2)K_BT`
(c) `(2/3) RT`
(d) `(3/2)("RT"/M)`
A body cools from 80° C to 70° C in 5 minutes and to 62° C in the next 5 minutes. Calculate the temperature of the surroundings.
If the temperature of a uniform rod is slightly increased by ∆t, its moment of inertia I about a line parallel to itself will increase by
The temperature of water at the surface of a deep lake is 2°C. The temperature expected at the bottom is
A person's skin is more severely burnt when put in contact with 1 g of steam at 100°C than when put in contact with 1 g of water at 100°C. Explain
The atmospheric temperature in the cities on sea-coast change very little. Explain
Two bodies at different temperatures are mixed in a calorimeter. Which of the following quantities remains conserved?
The mechanical equivalent of heat ____________ .
The heat capacity of a body depends on
(a) the heat given
(b) the temperature raised
(c) the mass of the body
(d) the material of the body
If heat is supplied to a solid, its temperature
(a) must increase
(b) may increase
(c) may remain constant
(d) may decrease
The temperature of an object is observed to rise in a period. In this period
(a) heat is certainly supplied to it
(b) heat is certainly not supplied to it
(c) heat may have been supplied to it
(d) work may have been done on it
A resistance thermometer reads R = 20.0 Ω, 27.5 Ω, and 50.0 Ω at the ice point (0°C), the steam point (100°C) and the zinc point (420°C), respectively. Assuming that the resistance varies with temperature as Rθ = R0 (1 + αθ + βθ2), find the values of R0, α and β. Here θ represents the temperature on the Celsius scale.
A metre scale made of steel is calibrated at 20°C to give correct reading. Find the distance between the 50 cm mark and the 51 cm mark if the scale is used at 10°C. Coefficient of linear expansion of steel is 1.1 × 10–5 °C–1.
A steel wire of cross-sectional area 0.5 mm2 is held between two fixed supports. If the wire is just taut at 20°C, determine the tension when the temperature falls to 0°C. Coefficient of linear expansion of steel is 1.2 × 10–5 °C–1 and its Young's modulus is 2.0 × 10–11 Nm–2.
A steel ball that is initially at a pressure of 1.0 × 105 Pa is heated from 20°C to 120°C, keeping its volume constant.
Find the pressure inside the ball. Coefficient of linear expansion of steel = 12 × 10–6 °C–1and bulk modulus of steel = 1.6 × 1011 Nm–2.
Define one mole.
Our normal body temperature is ______.
Two tumblers of A and B have water at 50°C temperature. If the water from A and B is poured into tumbler C. The temperature of C is ______.
Heat is measured in Celsius or centigrade.
Two identical beakers A and B contain equal volumes of two different liquids at 60°C each and is left to cool down. Liquid in A has a density of 8 × 102 kg/m3 and specific heat of 2000 J kg-1 K-1 while the liquid in B has a density of 103 kg m-3 and specific heat of 4000 J kg-1 K-1. Which of the following best describes their temperature versus time graph schematically? (assume the emissivity of both the beakers to be the same.)
The average kinetic energy of molecules of a gas is directly related to which physical quantity?
1 calorie is equal to how many joules?
The concept of thermal equilibrium, where heat flows between bodies until they reach the same temperature, is the basis of which law of thermodynamics?
