JEE · NEET Previous Year Question
Which of the following statements is true/correct
Topic: NEET PYQ
Answer: B. Full step-by-step solution below.
- ADuring clear nights, the temperature rises steadily upward near the ground level
- BNewton's law of cooling, an approximate form of Stefan's law, is valid only for natural convection
- CThe total energy emitted by a black body per unit time per unit area is proportional to the square of its temperature in the Kelvin scale
- DTwo spheres of the same material have radii and and temperatures 4000 K and 2000 K respectively. The energy radiated per second by the first sphere is greater than that radiated per second by the second sphere
Correct answer: B
Solution
(b) During clear nights object on surface of earth radiate out heat and temperature falls. Hence option (a) is wrong.The total energy radiated by a body per unit time per unit area E . Hence option (c) is wrong.
Energy radiated per second is given by
= , hence option (d) is wrong.
Newton's law is an approximate form of Stefan's law of radiation and works well for natural convection.
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