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.
Angle of the prism = 60°
Angle of minimum deviation (δ) = 20°
We know,
Angle of minimum deviation (δ) = 2i – A
or, δ = 2i – A
or, 2i = δ + A = 20° + 60° = 80°
or, i = 40°
OR
Given
μ = \text{c}\over\text{v}
or, v = \text{c}\over\text{μ}
= \text{3 × 10⁸}\over\text{1.5}
= 2 × 10⁸ m/s
More WBBSE Moderate level questions
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
Whether a concave lens is called a converging or diverging lens? Answer with reason.
A convex lens forms a 10 times magnified image of an object. If the length of the object is 5 cm, determine the length of the image.
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°
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]
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]
Define dispersion of light. How would you identify monochromatic light and composite light with the help of a prism? [1 + 2]
Write down the relationship between relative refractive index and absolute refractive index. On which factors does the relative refractive index of a medium depend? [1 + 2] OR Show that if a monochromatic light ray passes symmetrically through an equilateral prism then the angle of deviation of that ray will be minimum
Where is the image formed if the object is placed in between f and 2f of a convex lens ?
State whether the refractive index of a medium would increase or decrease if the angle of incidence is increased.
Write Snell's law of refraction of light. OR Write two characteristics of the image of an extended object formed when it is placed in between the optical centre and focus of a thin convex lens.
