If current in the core decreases, the strength of the magnetic field

Options

A. decreases
B. increases
C. sometimes decreases and sometimes increases
D. remains unchanged

Explanation

To solve the question "If current in the core decreases, the strength of the magnetic field," we will analyze the relationship between current and magnetic field strength.

### Step-by-Step Solution:

1. **Understand the Relationship**: The strength of the magnetic field (B) produced by a current-carrying conductor is directly proportional to the current (I) flowing through it. This relationship can be expressed mathematically as:
\[ B \propto I \]
where B is the magnetic field strength and I is the current.

2. **Identify the Variables**: In the equation for the magnetic field, we have:
- \( B \): Magnetic field strength
- \( I \): Current
- \( \mu_0 \): Permeability of free space (a constant)
- \( n \): Number of turns of the coil (if applicable)

The general formula can be expressed as:
\[ B = \mu_0 n I \]

3. **Analyze the Effect of Decreasing Current**: If the current (I) decreases, we can substitute this into the equation. Since B is directly proportional to I, a decrease in I will lead to a decrease in B. Mathematically, if I decreases:
\[ B \text{ decreases} \]

4. **Conclusion**: Therefore, if the current in the core decreases, the strength of the magnetic field will also decrease. The correct answer to the question is:
- **Option 1: Decreases**

### Final Answer:
If the current in the core decreases, the strength of the magnetic field decreases.

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