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A concave mirror of curvature 40 cm, used for shaving purposes produces image of double size as that of the object. Object distance must be ______.
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Answer the following question.
As per recent development, what is the nature of light? Wave optics and particle nature of light are used to explain which phenomena of light respectively?
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Range of temperature in a clinical thermometer, which measures the temperature of the human body, is
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A glass bottle completely filled with water is kept in the freezer. Why does it crack?
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If two temperatures differ by 25° C on Celsius scale, the difference in temperature on Fahrenheit scale is
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If α, β and γ are coefficients of linear, area l and volume expansion of a solid then
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Consider the following statements-
(I) The coefficient of linear expansion has dimension K-1.
(II) The coefficient of volume expansion has dimension K-1.
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Water falls from a hight of 200 m. What is the difference in temperature between the water at the top and bottom of a waterfall given that the specific heat of water is 4200 J kg-1 °C-1?
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Solve Numerical example.
A monochromatic ray of light strike the water (n = 4/3) surface in a cylindrical vessel at angle of incidence 53°. Depth of water is 36 cm. After striking the water surface, how long will the light take to reach the bottom of the vessel? [Angles of the most popular Pythagorean triangle of sides in the ratio 3:4:5 are nearly 37°, 53°, and 90°]
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Electric conduction through a semiconductor is due to:
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What is the importance of the energy gap in a semiconductor?
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Distinguish between action spectrum and absorption spectrum.
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Why is photolysis of water accompanied with non-cyclic photophosphorylation?
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Define emissive power and coefficient of emmision of a body.
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A metal sphere cools at the rate of 4°C / min. when its temperature is 50°C. Find its rate of cooling at 45°C if the temperature of surroundings is 25°C.
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Two copper spheres of radii 6 cm and 12 cm respectively are suspended in an evacuated enclosure. Each of them are at a temperature 15°C above the surroundings. The ratio of their rate of loss of heat is.................
- 2:1
- 1:4
- 1:8
- 8:1
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The dimensions of emissive power are ______.
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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]
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Compute the temperature at which the r.m.s. speed of nitrogen molecules is 832 m/s. [Universal gas constant, R = 8320 J/k mole K, molecular weight of nitrogen = 28.]
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The light from the Sun is found to have a maximum intensity near the wavelength of 470 nm. Assuming the surface of the Sun as a black body, the temperature of the Sun is _____________.
[Wien's constant b = 2 .898 x l0- 3mK]
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