Chapter-10 Light: Mirrors and Lenses — Online MCQ Test
SCIENCE · Grade 8 · CBSE(NCERT)
Practice Chapter-10 Light: Mirrors and Lenses with a free chapter-wise online MCQ test.
This chapter covers: reflection - refraction - plane mirror - concave mirror - convex mirror - concave lens - convex lens.
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Chapter-10 Light: Mirrors and Lenses — Important Questions & Answers
What is the phenomenon by which light bounces back when it hits a surface called?
- A. Refraction
- B. Reflection
- C. Dispersion
- D. Diffraction
Answer: B. Reflection
Reflection is the bouncing back of light when it strikes a surface, following the laws of reflection.
Reflection is the bouncing back of light when it strikes a surface, following the laws of reflection.
Which type of mirror always produces a virtual, erect, and diminished image?
- A. Plane mirror
- B. Concave mirror
- C. Convex mirror
- D. Both plane and concave
Answer: C. Convex mirror
A convex mirror always produces virtual, erect, and diminished images regardless of object position due to its diverging nature.
A convex mirror always produces virtual, erect, and diminished images regardless of object position due to its diverging nature.
An object is placed at the focal point of a concave mirror. What type of image will be formed?
- A. Real, inverted, same size
- B. Real, inverted, magnified
- C. Virtual, erect, magnified
- D. No image is formed (image at infinity)
Answer: D. No image is formed (image at infinity)
When an object is at the focal point of a concave mirror, the reflected rays are parallel and never converge, so no real image is formed.
When an object is at the focal point of a concave mirror, the reflected rays are parallel and never converge, so no real image is formed.
Compare the images formed by a concave mirror and a convex mirror when an object is placed at the same distance from each. Which statement is correct?
- A. Both form real images of the same size
- B. Both form virtual images of the same size
- C. Concave forms a real image while convex always forms a virtual image
- D. Convex forms a real image while concave always forms a virtual image
Answer: C. Concave forms a real image while convex always forms a virtual image
Concave mirrors can form both real and virtual images depending on object position, but convex mirrors always form virtual, erect, and diminished images.
Concave mirrors can form both real and virtual images depending on object position, but convex mirrors always form virtual, erect, and diminished images.
A light ray undergoes refraction at an air-glass interface. The incident angle is 45°. If the refractive index of glass is √2, what is the approximate refraction angle?
- A. 30°
- B. 25°
- C. 45°
- D. 60°
Answer: A. 30°
Using Snell's law: n₁sin(θ₁) = n₂sin(θ₂); 1×sin(45°) = √2×sin(θ₂); sin(θ₂) = (√2/2)/√2 = 1/2; θ₂ = 30°.
Using Snell's law: n₁sin(θ₁) = n₂sin(θ₂); 1×sin(45°) = √2×sin(θ₂); sin(θ₂) = (√2/2)/√2 = 1/2; θ₂ = 30°.