A person cannot see beyond a distance of 50 cm.The power of corrective lens required to see distant object is

Options

A. −1.5 D
B. −1.0D
C. −3 D
D. −2.0 D

Answer

To find the power of the corrective lens required for a person who cannot see beyond a distance of 50 cm, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Condition**: The person has a far point of 50 cm, which means they can only see objects clearly up to this distance. This condition indicates that the person is suffering from myopia (nearsightedness).

2. **Convert the Distance to Meters**: Since the standard unit for measuring lens power is in meters, we need to convert 50 cm to meters:
\[ \text{Distance (d)} = 50 \text{ cm} = 0.50 \text{ m} \]

3. **Use the Lens Formula**: The formula for the power (P) of a lens is given by:
\[ P = \frac{1}{f} \]
where \( f \) is the focal length in meters. For myopic correction, the focal length will be negative since it is a concave lens.

4. **Calculate the Focal Length**: The focal length required to correct the vision can be considered as the distance to the far point (in this case, -0.50 m):
\[ f = -0.50 \text{ m} \]

5. **Calculate the Power of the Lens**: Substitute the focal length into the power formula:
\[ P = \frac{1}{-0.50} = -2 \text{ diopters} \]

6. **Conclusion**: The power of the corrective lens required for the person to see distant objects clearly is -2 diopters.

### Final Answer:
The power of the corrective lens required is **-2 diopters**.

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