Which of the following is called heat radiation?

Options

A. X-rays
B. Gamma rays
C. Microwave
D. Infrared radiation

Explanation

To answer the question "Which of the following is called heat radiation?" we will analyze the options provided and determine which one corresponds to heat radiation.

### Step-by-Step Solution:

1. **Understanding Heat Radiation**:
- Heat radiation refers to the transfer of internal energy in the form of electromagnetic waves. It is important to identify which type of electromagnetic wave is associated with heat.

2. **Analyzing the Options**:
- **X-rays**: These are high-energy electromagnetic waves used primarily in medical imaging to view the inside of the body, particularly bones. They are not associated with heat radiation.
- **Gamma rays**: These are even higher-energy electromagnetic waves produced by nuclear reactions and certain types of radioactive decay. They are not related to heat radiation.
- **Microwaves**: These are used in communication and cooking (microwave ovens) but are not classified as heat radiation.
- **Infrared Radiation**: This type of radiation is known for its ability to transfer heat. Infrared radiation is emitted by all objects based on their temperature and is commonly associated with heat transfer.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Infrared Radiation**. It is the form of electromagnetic radiation that is commonly referred to as heat radiation.

### Final Answer:
The option that is called heat radiation is **Infrared Radiation**.

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