Advertisements
Advertisements
प्रश्न
Which one of the following materials cannot be used to make a lens?
विकल्प
Water
Glass
Plastic
Clay
उत्तर
Clay
Explanation:
since it is opaque and does not let light pass through it.
APPEARS IN
संबंधित प्रश्न
What is meant by a power of a lens? Define its SI unit.
What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm? Is the system a converging or a diverging lens? Ignore thickness of the lenses.
Kavita from 10th is using spectacles. The power of the lenses in her spectacles is –2.5 dioptre. Answer the following questions:
1) Which lenses are used in her spectacles?
2) State the defect of vision Kavita is suffering from.
3) Find the focal length of the lenses used in her spectacles
Name the physical quantity whose unit is dioptre.
Which type of lens has (a) a positive power, and (b) a negative power?
The focal length of a convex lens is 25 cm. What is its power?
What is the nature of a lens having a power of + 0.5 D?
A doctor has prescribed a corrective lens of power, −1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?
What do you understand by the power of a lens? Name one factor on which the power of a lens depends.
How does the power of a lens change if its focal length is doubled?
How is the sign (+ or -) of power of a lens related to its divergent or convergent action?
Express the power (with sign) of a concave lens of focal length 20 cm.
How does focal length of a lens change when red light incident on it is replaced by violet light? Give reason for your answer.
A normal eye is not able to see objects closer than 25 cm because
A double convex lens has two surfaces of equal radii R and refractive index \[m = 1 \cdot 5\]
A stick partly immersed in water appears to be bent. Draw a ray diagram to show the bending of the stick when placed in water and viewed obliquely from above.
If the lens is of focal length 25 cm. Calculate the power of the lens.
Focal length : metre : : power of lens : _______
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?
An object is kept at a distance of 1m from a lens of power +2D:
- Identify the type of lens.
- Calculate its focal length and distance of the image formed.
