Which of the following involves electromagnetic induction?

Options

A. A rod charged with electricity
B. An electric current producing a magnetic field
C. The relative motion between a magnet and a coil producing an electric current
D. A magnetic field exerting a force on a current carrying wire

Explanation

To determine which of the given options involves electromagnetic induction, we need to understand the concept of electromagnetic induction itself. Electromagnetic induction occurs when a change in magnetic field within a closed loop induces an electromotive force (EMF) and consequently an electric current in the loop.

Let's analyze each option step by step:

1. **First Option: A road charged with electricity**
- This option describes a road that is charged with electricity. However, this does not involve a changing magnetic field or relative motion between a magnet and a conductor. Therefore, this does not involve electromagnetic induction.

2. **Second Option: Electric current producing a magnetic field**
- This option describes the phenomenon where an electric current creates a magnetic field around it. While this is related to electromagnetism, it does not involve the induction process where a changing magnetic field induces an electric current. Hence, this option does not involve electromagnetic induction.

3. **Third Option: Relative motion between a magnet and a coil producing electric current**
- This option describes the scenario where there is relative motion between a magnet and a coil. According to Faraday's law of electromagnetic induction, when there is a change in magnetic flux through a coil (due to the relative motion), an EMF is induced, which can produce an electric current in the coil. This is a classic example of electromagnetic induction, making this option correct.

4. **Fourth Option: Magnetic field exerting force on a current-carrying wire**
- This option describes the force experienced by a current-carrying wire in a magnetic field, known as the Lorentz force. While this is a consequence of the interaction between magnetic fields and electric currents, it does not involve the induction process itself. Therefore, this option does not involve electromagnetic induction.

**Conclusion:**
The correct answer is the **third option**, which involves electromagnetic induction due to the relative motion between a magnet and a coil producing electric current.

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