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NEET - Physics Radiation Practice Q & A Page: 3
26294.A perfectly black body emits radiation at temperature $T_{1}$ K. If it is to radiate 16 times this power, its temperature $T_{2}$. will be
$T_{2} = 16 T_{1}$
$T_{2} = 8 T_{1}$
$T_{1} = 4 T_{1}$
$ T_{2} = 2 T_{1}$
26295.Unit of Stefan’s constant is given by
$W/mK^{2}$
$W/ m^{2}K^{2}$
$W^{2}/ m^{2}K^{2}$
W/ mK
26296.The flow of heat from a hot body to a cold body is an example of
Isothermal process
Reversible process
Adiabatic process
Irreversible process
26297.For which of the following process, the thermal conduction is maximum?
Combustion
Radiation
Convection
Conduction
26298.Three black bodies A, B and C in the form of cubes of sides in the ratio of 3: 4: 5 are kept at the same high temperature. The ratio of the quantity of heat lost per second by A, B and C will be
27: 64: 125
5: 4: 3
9: 16: 25
25: 16: 9
26299.A sphere, a cube and a thin circular plate all made of the same material and having the same mass are initially heated to a temperature of 300°C. which one of these cools faster?
Circular plate
Sphere
Cube
All will cool at the same rate
26300.A body cools from 60°C to 50°C in 10 minutes. If the room temperature is 25°C and assuming Newton’s law of cooling to hold good, the temperature of the body at the end of the next 10 minutes will be
38.5°C
40°C
42.85°C
45°C
26301.The emissive of a perfectly black body is
0
0.5
1
0.75
26302.The coefficient of transmission of a perfectly black body is
Zero
One
0.5
0.75
26303.An extremely hot star would appear to be
Yellow
Orange
Blue
Red
26304.When a black body is heated, it emits heat radiations of
Infrared wavelengths
Ultraviolet wavelengths
All wavelengths
A particular wavelengths
26305.A black body is at 300 K. It emits energy at a rate which is proportional to
(300)
(300)2
(300)4
(300)3
26306.An ideal black body is represented by
A metal coated with a black dye
A glass surface coated with coal tar
A hollow enclosure blackened from inside and having a small hole
A lump of charcoal heated to a high temperature
26307.The coefficient of transmission and coefficient of reflection for a given body at a given temperature are 0.33 and 0.64 respectively. Then the coefficient of emission of the same body at the same temperature will be
0.3
0.003
0.03
0.33
26308.If a black body is heated from 27°C to 927°C, then the ratio of the radiation emitted by the body at the two temperatures will be
1: 4
1: 16
1: 256
1: 64
26309.The correct equation out of the following is
E.Eb = a
$\dfrac{E}{E_{b}}=a$
$\dfrac{E_{b}}{E}=a$
$E.E_{b}=\dfrac{1}{a}$
26310.Two sphere of same material have radii r1 and r2. They are heated to same temperature and kept in same enclosure at low temperature their rates of loss of heat are in the ratio
$\dfrac{r_2^2}{r_1^2}$
$\dfrac{r_1^2}{r_2^2}$
$\dfrac{r_{1}}{r_{2}}$
$\dfrac{r_{2}}{r_{1}}$
26311.If the wavelengths of maximum intensity of radiation emitted by the moon and the sun are 10–4 m and 0.5 × 10–6m respectively, then the ratio of their temperature is
200
100
$\dfrac{1}{200}$
$\dfrac{1}{100}$
26312.The maximum wavelength of radiation emitted by a black body at 1227°C is λm. What is its maximum wavelength at 2227°C?
$\dfrac{ λm}{2}$
$\dfrac{ λm}{3}$
$\dfrac{3}{5}λm$
$\dfrac{9}{25}λm$
26313.A black body radiates energy at the rate of E watt m–2 at a temperature of T Kelvin. When the temperature is reduced to T/2 Kelvin, the radiant energy will become
$\left(\dfrac{E}{2}\right)$
$\left(\dfrac{E}{8}\right)$
$\left(\dfrac{E}{16}\right)$
None of the above
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