Lens Power Calculation
The power of a lens is defined as the reciprocal of its focal length when the focal length is measured in meters.
Formula and Calculation
The formula relating power ($P$) and focal length ($f$) is:
$ P = \frac{1}{f} $
Where:
- $P$ is the power of the lens in Diopters (D).
- $f$ is the focal length in meters (m).
Step-by-Step Solution
- Convert Focal Length: The given focal length is $f = 25\text{ cm}$. Convert this to meters:
$ f = 25\text{ cm} = \frac{25}{100}\text{ m} = 0.25\text{ m} $
- Calculate Power: Use the formula $P = \frac{1}{f}$ with the focal length in meters.
$ P = \frac{1}{0.25\text{ m}} $
$ P = 4\text{ D} $
Therefore, the power of the lens is $4\text{ D}$.
Similar Questions
- The ability of a medium to refract light is also expressed in terms of its:
- The center of the reflecting surface of a spherical mirror is a point called:
- The lens which is thin in the middle and thick at its periphery is called a:
- Which colour deviates the least when light passes through a prism?
- Shadows are formed when _____ objects come in the path of light.
- Which type of mirror is used by dentists to see large images of patients' teeth?
- The blue colour of the sky is due to the:
- Which kind of mirrors is used as rear view wing mirrors in vehicles?
- For a person with Hypermetropia or far-sightedness, the near point, is _____ farther away from the normal near point.
- Hypermetropia can be corrected by using:
Important Questions from Optics
Who was the first one to use a glass prism to obtain the spectrum of sunlight?
Twinkling of stars is due to:
In which a convex mirror is used?
A. Rear View mirrors in vehicles
B. Glass windows
C. Makeup Mirror
D. Kaleidoscope
An object is placed 10 cm in front of a lens. The image formed is real, inverted and of same size as the object. What is the focal length and nature of the lens?
The power of a lens is -2.5 D. The type of lens and its focal length are respectively:
