The law of electromagnetic induction have been used in the construction of

Options

A. galvanometer
B. voltmeter
C. electric motor
D. electric generator

Answer

To solve the question regarding the application of the law of electromagnetic induction, we will analyze each option provided and determine which one is constructed based on this law.

### Step-by-Step Solution:

1. **Understanding the Law of Electromagnetic Induction**:
- The law of electromagnetic induction, formulated by Michael Faraday, states that a change in magnetic flux through a coil induces an electromotive force (EMF) in the coil. This is known as Faraday's law of electromagnetic induction.

2. **Analyzing the Options**:
- **Option A: Galvanometer**:
- A galvanometer operates on the principle that a current-carrying conductor experiences a torque when placed in a magnetic field. It does not primarily rely on the induction of EMF due to changing magnetic flux. Therefore, this option is incorrect.

- **Option B: Voltmeter**:
- A voltmeter measures the potential difference across two points in a circuit and is based on Ohm's law. It does not directly utilize the principle of electromagnetic induction for its operation. Hence, this option is also incorrect.

- **Option C: Electric Motor**:
- An electric motor converts electrical energy into mechanical energy. It works on the principle that a current-carrying conductor in a magnetic field experiences a force. While it involves magnetic fields, it does not primarily rely on the induction of EMF from changing magnetic flux. Thus, this option is incorrect.

- **Option D: Electric Generator**:
- An electric generator converts mechanical energy into electrical energy by rotating a coil in a magnetic field, which induces an EMF according to Faraday's law of electromagnetic induction. This is the direct application of the law of electromagnetic induction. Hence, this option is correct.

3. **Conclusion**:
- The law of electromagnetic induction is fundamentally used in the construction of an **Electric Generator**.

### Final Answer:
The correct option is **D: Electric Generator**.

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