Very Short Answer Questions- Light: Mirrors and Lenses

Q1. What type of mirror is the inner side of a spoon?
Ans: The inner side of a spoon is a concave mirror. It curves inward and can converge light rays, often producing a magnified image when an object is held close to it.

Q2. What type of mirror is the outer side of a spoon?
Ans: The outer side of a spoon is a convex mirror. It curves outward and causes light rays to diverge, forming a smaller, erect, virtual image.

Q3. Define a spherical mirror.
Ans: A spherical mirror is a mirror whose reflecting surface is a part of a hollow sphere. Depending on which side is reflective, it may be concave or convex.

Q4. In a concave mirror, is the center curved inward or outward?
Ans: In a concave mirror, the centre of the reflecting surface is curved inward, towards the interior of the hollow sphere.

Q5. In which type of mirror is the reflecting surface curved outward?
Ans: In a convex mirror, the reflecting surface is curved outward, so parallel rays of light spread out after reflection.

Q6. What is placed on the glass surface to make a mirror reflective?
Ans: A thin reflective coating of metal, typically aluminium or silver, is placed on the glass surface to make it reflective.

Q7. How does a concave mirror form an image when the object is very close?
Ans: When an object is placed very close to a concave mirror (between the mirror and its principal focus), the mirror forms an erect, enlarged and virtual image that appears behind the mirror.

Q8. How does the image in a convex mirror appear at any distance?
Ans: In a convex mirror, the image is always erect, smaller than the object and virtual; it appears behind the mirror regardless of the object distance.

Q9. What type of image does a plane mirror always form?
Ans: A plane mirror always forms an erect image of the same size as the object; the image is virtual and appears at the same distance behind the mirror as the object is in front.

Q10. What is lateral inversion?
Ans: Lateral inversion is the left-right reversal of an image in a mirror so that the left side of the object appears as the right side in the image and vice versa.

Q11. Which mirror is used as a reflector in torches and headlights?
Ans: A concave mirror is used as a reflector in torches and headlights because it collects light from the bulb and reflects it into a parallel beam for a strong, focused beam of light.

Q12. Why is a convex mirror used as a vehicle's side-view mirror?
Ans: A convex mirror gives a wider field of view and forms smaller, erect images, allowing the driver to see more area behind and to the side of the vehicle.

Q13. What type of mirror is used in modern telescopes?
Ans: Modern reflecting telescopes use a large concave mirror to gather and focus light from distant objects, producing clearer and brighter images.

Q14. What is the First Law of Reflection?
Ans: The First Law of Reflection states that the angle of incidence equals the angle of reflection; both angles are measured with respect to the normal at the point of incidence.

Q15. What is the Second Law of Reflection?
Ans: The Second Law of Reflection states that the incident ray, the normal to the surface at the point of incidence, and the reflected ray all lie in the same plane.

Q16. Name the type of mirror that converges parallel light rays.
Ans: A concave mirror converges parallel light rays; such rays meet at the mirror's principal focus.

Q17. Why can a concave mirror burn paper in sunlight?
Ans: A concave mirror focuses sunlight to a small spot at its principal focus, concentrating the energy and producing enough heat at that point to burn paper.

Q18. What is a lens made of?
Ans: A lens is made of a transparent material such as glass or plastic, with its surfaces shaped and polished so that it can refract (bend) light.

Q19. Which lens is thicker in the middle than at the edges?
Ans: A convex lens is thicker in the middle than at the edges; it is a converging lens that brings parallel light rays together.

Q20. Which lens is thicker at the edges than in the middle?
Ans: A concave lens is thicker at the edges than in the middle; it is a diverging lens that makes parallel rays spread out.

Q21. How does a convex lens change an image when the object is very close?
Ans: When an object is very close to a convex lens (within its focal length), the lens forms an erect, enlarged and virtual image; this principle is used in a magnifying glass.

Q22. How does a concave lens form an image at any distance?
Ans: A concave lens always forms an erect, smaller and virtual image for objects at any distance; the image appears on the same side of the lens as the object.

Q23. What type of lens is called a converging lens?
Ans: A convex lens is called a converging lens because it brings parallel light rays together to meet at its principal focus.

Q24. What type of lens is called a diverging lens?
Ans: A concave lens is called a diverging lens because it causes parallel light rays to spread out as if they came from a point (a virtual focus).

Q25. Which part of the human eye acts as a convex lens?
Ans: The eye's natural crystalline lens acts as a convex lens; it helps to refract and focus light onto the retina so we can form clear images.