Power of a lens is + 3 D. What will be the focal length of the lens?

Options

A. `1/3 cm`
B. `100/3 cm`
C. `300 cm`
D. `1/300 cm`

Explanation

To find the focal length of a lens given its power, we can use the relationship between power (P) and focal length (f). The formula is:

\[ P = \frac{100}{f} \]

where:
- P is the power of the lens in diopters (D)
- f is the focal length in centimeters (cm)

Given that the power of the lens is +3 D, we can substitute this value into the formula.

### Step-by-Step Solution:

1. **Write down the formula for power:**
\[ P = \frac{100}{f} \]

2. **Substitute the given power into the formula:**
\[ 3 = \frac{100}{f} \]

3. **Rearrange the equation to solve for focal length (f):**
\[ f = \frac{100}{3} \]

4. **Calculate the value of f:**
\[ f \approx 33.33 \text{ cm} \]

Thus, the focal length of the lens is approximately 33.33 cm.

### Final Answer:
The focal length of the lens is \( \frac{100}{3} \) cm or approximately 33.33 cm.

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