State whether the following statements are true or false :
MCB works on the heating effect of electric current.

Explanation

To determine whether the statement "MCB works on the heating effect of electric current" is true or false, we can analyze the function of an MCB (Miniature Circuit Breaker) and the principles behind it.

### Step-by-Step Solution:

1. **Understanding MCB**:
- MCB stands for Miniature Circuit Breaker. It is a safety device used in electrical circuits to prevent overload and short circuits.

2. **Function of MCB**:
- The primary function of an MCB is to automatically disconnect the circuit when it detects an excess flow of current. This is crucial to prevent damage to electrical appliances and reduce the risk of fire.

3. **Heating Effect of Electric Current**:
- When electric current flows through a conductor, it generates heat due to resistance. This is known as the heating effect of electric current. If the current exceeds a certain limit, it can cause the conductor to overheat, potentially leading to damage or fire.

4. **MCB Operation**:
- MCBs are designed to trip (disconnect) when the current exceeds a predefined threshold, which is often related to the heating effect. When the current is too high, the heat generated can cause the MCB to trip, breaking the circuit and stopping the flow of electricity.

5. **Conclusion**:
- Since MCBs operate based on the principle of detecting excessive current, which is directly related to the heating effect of electric current, we can conclude that the statement is **True**.

### Final Answer:
The statement "MCB works on the heating effect of electric current" is **True**.

---