Light is a form of energy that travels in the form of waves. It behaves in two main ways when it interacts with surfaces: reflection and refraction.
Reflection of Light:
- Reflection is the bouncing back of light from a surface.
- Law of Reflection: Angle of incidence = Angle of reflection.
- Example: Mirror reflects light to form an image.
Refraction of Light:
- Refraction is the bending of light when it passes from one medium to another.
- The amount of bending depends on the refractive index.
- Example: A straw looks bent in water due to refraction.
Key Differences Between Reflection and Refraction:
- Reflection: Light bounces off a surface.
- Refraction: Light bends when passing through different media.
Practice Questions PDF
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Questions on Light – Reflection and Refraction
Showing 61–90 of 12661.Why is a real image always inverted, while a virtual image is always erect (for single mirror/lens setups)? 62.What is meant by the principal axis of a spherical mirror? 63.A light ray passes from a medium A to a medium B. If the angle of incidence is 45° and the angle of refraction is 30°, calculate the refractive index of medium B with respect to medium A. (sin 45° = 0.707, sin 30° = 0.5) 64.Why do convex lenses have a real focal point, while concave lenses have a virtual focal point? 65.Assertion (A): A magnifying glass uses a convex lens. Reason (R): A convex lens can form a virtual, magnified image. 66.An object is placed 10 cm from a convex mirror of focal length 15 cm. Calculate the position and nature of the image. 67.How does the speed of light change when it passes from a rarer medium to a denser medium? What effect does this have on its wavelength and frequency? 68.A ray of light incident normally on a plane mirror. What is the angle of reflection? 69.What is the relationship between the radius of curvature (R) and the focal length (f) of a spherical mirror? 70.Define power of a lens and state its SI unit. 71.A boy is trying to focus sunlight using a spherical mirror. At what position should he place the paper to get the sharpest image of the sun? 72.Assertion (A): It is difficult to read a newspaper through a sheet of clear glass placed on it. Reason (R): The refractive index of glass is different from that of air. 73.A pencil appears thicker and shorter when viewed from the side through a cylindrical glass of water. Explain this phenomenon. 74.An object is placed 10 cm in front of a concave mirror producing a real image 20 cm from the mirror. Calculate the focal length of the mirror. 75.Why are large parabolic mirrors used in solar furnaces? 76.A student holds a reading glass (convex lens) in the sun to burn a piece of paper. Where should the paper be placed relative to the lens? 77.If a convex lens is immersed in a liquid having a refractive index greater than that of the lens material, how will its focal length and nature change? 78.A plane mirror is rotated by an angle θ. By what angle does the reflected ray rotate? 79.An object is placed at a distance equal to twice the focal length (2F) of a convex lens. Describe the characteristics of the image formed. 80.Which of the following optical phenomena is responsible for the twinkling of stars? 81.Assertion (A): The power of a convex lens is positive. Reason (R): A convex lens is a converging lens and its focal length is positive. 82.Why does a convex mirror always produce a virtual, erect, and diminished image, regardless of the object's position? 83.A light ray travels from a medium X to a medium Y. The speed of light in X is 2.5 x 10⁸ m/s, and in Y it is 2.0 x 10⁸ m/s. What is the refractive index of medium Y with respect to medium X? 84.A student uses a concave mirror to project the image of a candle flame on a screen. If the image formed is inverted and three times the size of the flame, and the screen is 60 cm from the mirror, what is the object distance? 85.An object is placed at a distance of 10 cm from a plane mirror. If the object is moved 5 cm towards the mirror, how does the distance between the object and its image change? 86.A light ray passes through a rectangular glass slab. Explain why the emergent ray is parallel to the incident ray but is laterally displaced. 87.A doctor prescribes a corrective lens of power +2.0 D. Is this lens converging or diverging, and what is its focal length? 88.Why are silvered surfaces used in mirrors? 89.Two lenses, one convex with focal length +20 cm and another concave with focal length -10 cm, are placed in contact. What is the power of this combination? 90.Under what conditions will a convex lens form a virtual image? Draw a ray diagram to support your answer. (No drawing expected here, just descriptive answer.)