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1. |
The flow of heat from a hot body to a cold body is an example of (MHT-CET-2001) (a) Isothermal process (b) Reversible process (c) Adiabatic process (d) Irreversible process |
Answer: (d) |
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2. |
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 (a) 27: 64: 125 (b) 5: 4: 3 (c) 9: 16: 25 (d) 25: 16: 9 |
Answer: (c) |
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3. |
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? (a) Circular plate (b) Sphere (c) Cube (d) All will cool at the same rate |
Answer: (a) |
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4. |
The emissive of a perfectly black body is (a) 0 (b) 0.5 (c) 1 (d) 0.75 |
Answer: (c) |
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5. |
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 (a) 200 (b) 100 (c) (d) |
Answer: (c) |
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6. |
The coefficient of transmission of a perfectly black body is (a) Zero (b) One (c) 0.5 (d) 0.75 |
Answer: (a) |
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7. |
When a black body is heated, it emits heat radiations of (a) Infrared wavelengths (b) Ultraviolet wavelengths (c) All wavelengths (d) A particular wavelengths |
Answer: (c) |
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8. |
An ideal black body is represented by (a) A metal coated with a black dye (b) A glass surface coated with coal tar (c) A hollow enclosure blackened from inside and having a small hole (d) A lump of charcoal heated to a high temperature |
Answer: (c) |
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9. |
The temperature of a furnace is 2327°C and the intensity is maximum in its radiation spectrum at 1200 (a) 6500 K (b) 6000 K (c) 4800 K (d) 7500 K |
Answer: (a) |
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10. |
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 (a) 0.3 (b) 0.003 (c) 0.03 (d) 0.33 |
Answer: (c) |
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11. |
The correct equation out of the following is (MHT-CET-2006) (a) (b) (c) (d) |
Answer: (b) |
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12. |
The maximum wavelength of radiation emitted by a black body at 1227°C is λm. What is its maximum wavelength at 2227°C? (a) (b) (c) (d) |
Answer: (c) |
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13. |
According to Prevost’s theory of heat exchange, the heat exchange shops at (MHT-CET-2007) (a) 0°C (b) – 5°C (c) – 273°C (d) – 273 K |
Answer: (c) |
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14. |
The rate of cooling of a body is 0.5°C/minute, when the body is 50°C above the surrounding. What is the rate of cooling if the body is 30°C above the surrounding? (a) 24°C/hour (b) 18°C/hour (c) 30°C/hour (d) 12°C/hour |
Answer: (b) |
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15. |
Coefficient of transmission and coefficient of reflection for a given body are 0.22 and 0.74 respectively. Then, at a given temperature, the coefficient of emission for the body is (MHT-CET-2005) (a) 0.4 (b) 0.04 (c) 0.96 (d) 0.22 |
Answer: (b) |
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16. |
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 (a) 1: 4 (b) 1: 16 (c) 1: 256 (d) 1: 64 |
Answer: (c) |
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17. |
A body cools from 100°C to 70°C in 8 minutes. If the room temperature is 15°C and assuming Newton’s law of cooling holds good, then time required for the body to cool from 70°C to 40°C is (MHT-CET-2005) (a) 14 s (b) 10 s (c) 8 s (d) 5 s |
Answer: (a) |
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18. |
A body radiates heat at the rate of 4 cal/m2/s, when its temperature is 227°C. what is the heat radiated by the same body when its temperature is 727°C? (a) 8 cal/m2/s (b) 16 cal/m2/s (c) 64 cal/m2/s (d) 32 cal/m2/s |
Answer: (c) |
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19. |
Two thermometers A and B exposed to sunlight. The value of A is painted black but that of B is not painted. The correct statement regarding this case is (MHT-CET-1999) (a) Temperature of B will rise faster (b) Temperature of A will remain more than B (c) Both of A and B show equal rise from the beginning (d) Temperature of A will rise faster than B but the final temperature will be same in both |
Answer: (d) |
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20. |
Two spheres made of same material have radii in the ratio 2: 1. if both the spheres are at same temperature, then what is the ratio of heat radiation energy emitted per second by them? (MHT-CET-2004) (a) 1: 4 (b) 4: 1 (c) 3: 4 (d) 4: 3 |
Answer: (b) |
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21. |
The temperature of a black body is gradually increased. The colour of the body will change from (a) White-green-red (b) Red-yellow-blue (c) Red-violet-yellow (d) Yellow-green-red |
Answer: (b) |
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22. |
Radiation emitted by a surface is directly proportional to (MHT-CET-2000) (a) Third power of its temperature (b) Equal to its temperature (c) Twice power of its temperature (d) Fourth power of its temperature |
Answer: (d) |
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23. |
The coefficient of absorption of perfectly black body is (MHT-CET-2004) (a) 1 (b) 0 (c) 0.75 (d) None of these |
Answer: (a) |
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24. |
Two bodies A and B at temperatures T1 K and T2 K respectively have the same dimensions. Their emissivities are in the ratio of 1: 3. if they radiate the same amount of heat per unit time, then the relation between their temperatures is given by (a) (b) (c) (d) |
Answer: (c) |
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25. |
A body radiates heat at the ate of 5 cal/m2-s when its temperature is 227°C. the heat radiated by the same body when its temperature is 727°C is (MHT-CET-2007) (a) 10 cal/m2-s (b) 20 cal/m2-s (c) 40 cal/m2-s (d) 80 cal/m2-s |
Answer: (d) |
. If the intensity in the spectrum of a star is maximum at 4800
