Q1. When light passes through a convex lens, what type of lens is it?
a) Diverging lens
b) Converging lens
c) Plano-concave lens
d) Plano-convex lens
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Correct Answer: b) Converging lens
Explanation: A convex lens is a converging lens because it causes parallel rays of light to converge to a focal point after refraction.
Q2. What happens to light rays that pass through the optical center of a lens?
a) They refract and converge
b) They refract and diverge
c) They pass undeviated
d) They scatter in all directions
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Correct Answer: c) They pass undeviated
Explanation: Light rays passing through the optical center of a lens do not deviate from their path and continue in a straight line.
Q3. Which type of lens is thicker at the center than at the edges?
a) Concave lens
b) Convex lens
c) Biconcave lens
d) Biconvex lens
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Correct Answer: d) Biconvex lens
Explanation: A biconvex lens is thicker at the center than at the edges and has two convex surfaces. It is a converging lens.
Q4. What is the point where parallel rays of light converge or appear to diverge after passing through a lens called?
a) Optical center
b) Principal axis
c) Focal point
d) Vertex
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Correct Answer: c) Focal point
Explanation: The focal point of a lens is the point where parallel rays of light converge or appear to diverge after passing through the lens.
Q5. Which type of lens causes parallel rays of light to diverge after refraction?
a) Convex lens
b) Concave lens
c) Plano-convex lens
d) Plano-concave lens
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Correct Answer: b) Concave lens
Explanation: A concave lens is a diverging lens that causes parallel rays of light to diverge away from each other after refraction.
Q6. In which type of lens is the focal length negative?
a) Convex lens
b) Concave lens
c) Plano-convex lens
d) Plano-concave lens
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Correct Answer: b) Concave lens
Explanation: For a concave lens, the focal length is negative since the focal point is virtual and located on the opposite side of the incoming light.
Q7. What is the name given to the point on the principal axis where all incident rays parallel to the axis converge or appear to diverge from after refraction by a lens?
a) Optical center
b) Focal point
c) Vertex
d) Principal focus
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Correct Answer: b) Focal point
Explanation: The focal point of a lens is the point where all incident rays parallel to the principal axis converge or appear to diverge from after refraction.
Q8. When a ray of light passes through a convex lens and is refracted, what happens to its direction?
a) It bends towards the principal axis
b) It bends away from the principal axis
c) It remains parallel to the principal axis
d) It scatters in all directions
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Correct Answer: a) It bends towards the principal axis
Explanation: A convex lens converges light rays towards the principal axis, causing them to bend towards it after refraction.
Q9. What is the name given to the point on the principal axis where all incident rays passing through it emerge parallel to each other after refraction by a lens?
a) Optical center
b) Focal point
c) Vertex
d) Principal focus
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Correct Answer: a) Optical center
Explanation: The optical center of a lens is the point on the principal axis where all incident rays passing through it emerge parallel to each other after refraction.
Q10. Which of the following lenses can form a virtual and erect image for a real object?
a) Convex lens only
b) Concave lens only
c) Both convex and concave lenses
d) Neither convex nor concave lenses
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Correct Answer: c) Both convex and concave lenses
Explanation: Both convex and concave lenses can form virtual and erect images, depending on the position of the object relative to the lens and the lens characteristics.