SI unit of heat is

Options

A. erg
B. joule
C. calorie
D. none of these

Explanation

To determine the SI unit of heat, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Heat**:
- Heat is a form of energy that is transferred between systems or objects with different temperatures (thermal energy).

2. **Identify the SI Unit System**:
- The SI (International System of Units) is a standardized system of measurement used globally. It includes various units for different physical quantities.

3. **Look for the SI Unit of Energy**:
- Since heat is a form of energy, we need to identify the SI unit that measures energy.

4. **Know the Common Units of Heat**:
- Common units of heat include joules, calories, and ergs. However, not all of these are SI units.

5. **Determine the Correct SI Unit**:
- The SI unit of energy, which includes heat, is the joule (J).

6. **Conclusion**:
- Therefore, the SI unit of heat is joule.

### Final Answer:
The SI unit of heat is **joule** (Option 2).

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