A man cannot see the objects clearly beyond a distance of 50 cm. The focal length of the lens required for the correction is Only one correct answerA.150 cmB.120 cmC.100 cmD.50 cm

The man's far point is at 50 cm, which is less than infinity. This means he is suffering from myopia or nearsightedness.

The formula to calculate the focal length of the lens required for correction is:

1/f = 1/v - 1/u

Where:

• f is the focal length of the lens
• v is the image distance (which is at the far point, so -50 cm in this case)
• u is the object distance (which is at infinity)

Substituting the values into the formula:

1/f = 1/(-50) - 1/∞

Since 1/∞ is practically zero, the formula simplifies to:

1/f = -1/50

Therefore, f = -50 cm.

However, in optics, a negative focal length indicates a diverging lens, but for myopia, a converging lens is required. Therefore, the focal length of the lens required for correction is +50 cm.

So, the correct answer is D. 50 cm.