Which of the following is the fundamental significance of the Faraday’s discovery?

Options

A. A changing magnetic field can exert a force on the stationary charge
B. A changing magnetic field can exert a force on the neutral particle
C. A constant magnetic field can exert a force on the stationary charge
D. A constant magnetic field can exert a force on the neutral particle

Answer

To answer the question regarding the fundamental significance of Faraday's discovery, we will analyze the principles of electromagnetic induction as established by Faraday.

### Step-by-Step Solution:

1. **Understanding Faraday's Law of Electromagnetic Induction**:
- Faraday's law states that an electromotive force (emf) is induced in a conductor when it is placed in a varying magnetic field. This can be mathematically expressed as:
\[ \text{emf} = -\frac{d\Phi}{dt} \]
where \(\Phi\) is the magnetic flux through the conductor.

2. **Magnetic Flux**:
- The magnetic flux (\(\Phi\)) is defined as the product of the magnetic field (\(B\)) and the area (\(A\)) through which the field lines pass, given by:
\[ \Phi = B \cdot A \]
- When the magnetic field is varying, the flux changes over time, which induces an emf in the conductor.

3. **Induced EMF**:
- If the magnetic field is changing, then \(\frac{d\Phi}{dt} \neq 0\), which leads to a non-zero induced emf. This induced emf can cause a current to flow if the circuit is closed.

4. **Significance of the Discovery**:
- The fundamental significance of Faraday's discovery lies in the fact that it established the principle that a changing magnetic field can induce an electric current in a conductor. This principle is foundational for many technologies, including electric generators and transformers.

5. **Evaluating the Options**:
- Now, we will evaluate the given options (not provided in the question but assumed to be related to the effects of magnetic fields on charges):
- **Option 1**: A changing magnetic field can exert a force on a stationary charge. (Correct)
- **Option 2**: A constant magnetic field can exert a force on a stationary charge. (Incorrect)
- **Option 3**: A constant magnetic field can exert a force on a neutral particle. (Incorrect)
- **Option 4**: A changing magnetic field can exert a force on a neutral particle. (Incorrect)

6. **Conclusion**:
- Based on the evaluation, the correct answer is that a changing magnetic field can exert a force on a stationary charge, which is the fundamental significance of Faraday's discovery.

### Final Answer:
The fundamental significance of Faraday's discovery is that a changing magnetic field can induce an electromotive force (emf) in a conductor, leading to the generation of electric current.