Q. No.Colour of shining bright star is an indication of its
(1) Distance from the earth
(2) Size
(3) Temperature
(4) Mass
(1) Distance from the earth
A black body at \(200~\text{K}\) is found to emit maximum energy at a wavelength of \(14~\mu \text{m}\). When its temperature is raised to \(1000~\text{K}\), the wavelength at which maximum energy is emitted will be:
| 1. | \(14~\mu\text{m}\) | 2. | \(70~\mu\text{m}\) |
| 3. | \(2.8~\mu\text{m}\) | 4. | \(2.8~\text{nm}\) |
If the temperature of the sun becomes twice its present temperature, then:
| 1. | Radiated energy would be predominantly in the infrared range. |
| 2. | Radiated energy would be primarily in the ultraviolet range. |
| 3. | Radiated energy would be predominantly in the X-ray region |
| 4. | Radiated energy would become twice as strong as it is now. |
The maximum energy in the thermal radiation from a hot source occurs at a wavelength of cm. According to Wein's law, the temperature of the source (on Kelvin scale) will be n times the temperature of another source (on Kelvin scale) for which the wavelength at maximum energy is cm. The value n is
(a) 2 (b) 4
(c) (d) 1
How is the temperature of stars determined by ?
(1) Stefan’s law
(2) Wein’s displacement law
(3) Kirchhoff’s law
(4) Ohm’s law
On increasing the temperature of a substance gradually, which of the following colours will be noticed by you ?
(1) White
(2) Yellow
(3) Green
(4) Red
A black body has a maximum wavelength at a temperature of \(2000~\text K.\) Its corresponding wavelength at temperatures of \(3000~\text K\) will be:
| 1. | \({3 \over 2} \lambda_m\) | 2. | \({2 \over 3} \lambda_m\) |
| 3. | \({4 \over 9} \lambda_m\) | 4. | \({9 \over 4} \lambda_m\) |
A black body at a temperature of 1640 K has the wavelength corresponding to maximum emission equal to 1.75 . Assuming the moon to be a perfectly black body, the temperature of the moon, if the wavelength corresponding to maximum emission is 14.35 m is
(1) 100 K
(2) 150 K
(3) 200 K
(4) 250 K
A particular star (assuming it as a black body) has a surface temperature of about . The wavelength in nanometers at which its radiation becomes maximum is -
(b = 0.0029 mK)
(1) 48
(2) 58
(3) 60
(4) 70
The intensity of radiation emitted by the sun has its maximum value at a wavelength of 510 nm and that emitted by the north star has the maximum value at 350 nm. If these stars behave like black bodies, then the ratio of the surface temperature of the sun and north star is
(1) 1.46
(2) 0.69
(3) 1.21
(4) 0.83
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