There is a black spot on a body. If the body is heated and carried in dark room then it glows more. This can be explained on the basis of

Options

A. Newton's law of cooling
B. Wein's law
C. Kirchoff's law
D. Stefan's law

Explanation

To solve the question, we need to understand the phenomenon described and the relevant laws of thermodynamics and heat transfer.

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- We have a body with a black spot on it. When this body is heated and taken into a dark room, it glows more than the rest of the body.

2. **Identifying the Relevant Law**:
- The phenomenon can be explained using Kirchhoff's law of thermal radiation, which states that at thermal equilibrium, the emissive power of a body (how much thermal radiation it emits) is directly related to its absorptive power (how much thermal radiation it absorbs).

3. **Applying Kirchhoff's Law**:
- Kirchhoff's law implies that a perfect absorber (black body) is also a perfect emitter. This means that if a body absorbs more radiation (like the black spot), it will also emit more radiation when heated.

4. **Behavior of the Black Spot**:
- The black spot absorbs more heat when the body is heated. When the body is taken into a dark room, the black spot will emit this absorbed energy as thermal radiation, causing it to glow more brightly compared to the other parts of the body.

5. **Conclusion**:
- Therefore, the increased glow of the black spot when heated in a dark room can be explained by Kirchhoff's law, which relates the emissive power and absorptive power of the body.

### Final Answer:
The phenomenon is explained on the basis of **Kirchhoff's law of thermal radiation**.

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