# The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?

**Given: **The far point of a myopic person is 80 cm in front of the eye.

**To: **To find the nature and power of the lens required to correct the problem.

**Solution:**

The person is suffering from myopia. And this person needs a concave lens to correct the defect. The lens should be such that an object at infinity must form its image at the far point of $80\ cm$ to make it visible to the myopic person.

The power of the lens can be obtained as:

**The formula for the power of the lens$\rightarrow$**

$\boxed{P=\frac{1}{f}}$

$P\rightarrow$ Power of the lens

$f\rightarrow$ focal length of the lens

It is given, $f=-80\ cm=-0.8\ m$

$P=\frac{1}{-0.8\ m}$

$=-1.25\ D$

Therefore,

**Power of the lens:**

The power of the lens is $-1.25\ D$.

**Nature of the lens:**

$(-ve)$ sign implies that it is a concave lens. It is diverging in nature.

Related Articles

- The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).
- Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25 cm.
- A lens has a focal length of, −10 cm. What is the power of the lens and what is its nature?
- What is the power of a convex lens whose focal length is 80 cm?
- (a) What is meant by the power of accommodation of an eye?(b) A person with a myopic eye cannot see objects beyond 1.2 m directly. What should be the type of the corrective lens used? What would be its power?
- What is the high converging power of eye lens?
- A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?
- What is the far point and near point of an eye with normal vision?
- What is the nature of a lens whose power is, −4 D?
- When an object is placed 10 cm in front of lens A, the image is real, inverted, magnified and formed at a great distance. When the same object is placed 10 cm in front of lens B, the image formed is real, inverted and same size as the object.(a) What is the focal length of lens A?(b) What is the focal length of lens B?(c) What is the nature of lens A?(d) What is the nature of lens B?
- What is the:(a) far point of a normal human eye?(b) near point of a normal human eye?
- (a) What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:(i) the eye-defect long-sightedness.(ii) correction of long-sightedness by using a lens.(b) An eye has a near point distance of 0.75 m. What sort of lens in spectacles would be needed to reduce the near point distance to 0.25 m? Also calculate the power of lens required. Is this eye long-sighted or short-sighted?(c) An eye has a far point of 2 m. What type of lens in spectacles would be needed to increase the far point to infinity? Also calculate the power of lens required. Is this eye long-sighted or short-sighted?
- Define power of a lens. What is its unit? One student uses a lens of focal length 50 cm and another of -50 cm. What is the nature of the lens and its power used by each of them?
- What is the nature of a lens having a power of + 0.5 D?
- Two lenses A and B have focal lengths of +20 cm and, −10 cm, respectively.(a) What is the nature of lens A and lens B?(b) What is the power of lens A and lens B?(c) What is the power of combination if lenses A and B are held close together?

##### Kickstart Your Career

Get certified by completing the course

Get Started
To Continue Learning Please Login

Login with Google