The geometric length of a bar magnet is `24cm`. The length of the magnet is

Options

A. `24cm`
B. `28.8cm`
C. `20cm`
D. `30cm`

Explanation

To find the length of the bar magnet based on its geometric length, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- The **geometric length** of a bar magnet is the total length measured from one end to the other.
- The **magnetic length** is the effective length of the magnet, which is less than the geometric length due to the positioning of the magnetic poles.

2. **Given Data**:
- Geometric length of the bar magnet = 24 cm.

3. **Relation Between Geometric Length and Magnetic Length**:
- It is known that the magnetic length of a bar magnet is approximately \( \frac{5}{6} \) of its geometric length.

4. **Calculate the Magnetic Length**:
- To find the magnetic length, we can use the formula:
\[ \text{Magnetic Length} = \frac{5}{6} \times \text{Geometric Length} \]
- Substituting the given geometric length:
\[ \text{Magnetic Length} = \frac{5}{6} \times 24 \, \text{cm} \]

5. **Perform the Calculation**:
- First, calculate \( \frac{5 \times 24}{6} \):
\[ = \frac{120}{6} = 20 \, \text{cm} \]

6. **Conclusion**:
- The length of the magnet is 20 cm.

### Final Answer:
The length of the magnet is **20 cm**.

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