QQuestion
Draw refracted rays for the incident rays which are parallel to the principal axis of a convex lens. Mark focus (F). [3]
OR
Explain the converging action of a convex lens. [3]
✓Answer
Ray Diagram for convex lens:
OR
Converging action of the convex lens as a combination of prisms:
A lens is made up of a set of prisms, the prisms in the upper part of a convex lens have their bases downwards, while the prisms in the lower part of the lens have their bases upwards. When a beam of parallel rays of light incident on a convex lens, the prisms in the upper part of the lens bend the incident rays downward and the prisms in the lower part of the lens bend the incident rays upwards. The central part which is a parallel sided glass block passes the incident ray undeviated. Thus the convex lens converges the parallel beam of light to a point called principal focus (F) of the lens and hence a convex lens is called a converging lens.
Related Questions
More WBBSE Moderate level questions
A light is incident from air medium on another medium. If the refractive index of this medium is 1.5 and the wavelength of light in this medium is 4000 Å what is the wavelength of light in the air medium ? What is the velocity of the light in this medium? [3] OR As a result of refraction of light through an equilateral prism the angle of deviation becomes 40°. If the path of the ray through the prism is parallel to the base of the prism, determine the angle of incidence at the first surface of prism. [3]
What is long-sightedness? What type of lens is used to remedy this defect? [2+1]
Establish the relationship between radius of curvature (r) and focal length (f) for a convex mirror. Write one use of a concave mirror. [2+1]
At what angle must a light ray fall on the surface of an equilateral prism so that its angle of minimum deviation will be 20°? OR Calculate the time required by a ray of light to traverse a glass slab of thickness 2 mm. The refractive index of glass=1.5.
The magnified virtual image is formed by (a) convex mirror (b) convex lens (c) plane mirror (d) concave lens
The equation expressing the correlation between refractive index and wavelength of light is (a) μ = A + B/λ (b) μ = A + Bλ² (c) μ = Aλ + B (d) μ = A + B/λ²
If a reflected ray from a concave mirror makes an angle of 45° with the normal, the angle of incidence will be 90° 22.5° 135° 45°
What is meant by the principal axis of a concave lens?
Determine the angle of deviation for the refraction of light rays from rarer to denser medium. [2] (angle of incidence = i, angle of refraction = r) OR Why do the green leaves of trees appear 'green' in sunlight? [2]
If the refractive indices of a medium for red and blue colours of light are μr and μb respectively, which one is greater in magnitude?
Which type of mirror is used in the headlight of a motor car?
Is it possible to form a virtual image of shorter length than the length of the object by any mirror?