Light: Mirrors and Lenses — Class 8 MCQs with Answers

Light: Mirrors and Lenses — important questions & MCQs with answers (Class 8 Science)

6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.

0 of 6 answered

1. Q1 of 6Easy

   The bouncing back of light from a surface is called:

   ArefractionBabsorptionCdispersionDreflection
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   Answer: reflection

   Explanation: Reflection is light bouncing back off a surface; refraction is bending as light passes into a different medium, and dispersion is light splitting into colours.

2. Q2 of 6Easy

   The image in a plane mirror is:

   Ainverted and largerBupside downCsmallerDerect and the same size as the object
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   Answer: erect and the same size as the object

   Explanation: A plane mirror always forms an erect, same-size image of the object — never magnified, diminished, or inverted, unlike curved mirrors.

3. Q3 of 6Medium

   A concave mirror can form a magnified, erect image when the object is:

   Aclose to the mirrorBvery far awayCbehind the mirrorDat infinity
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   Answer: close to the mirror

   Explanation: Held within its focal length, close to the mirror, a concave mirror produces a magnified, erect, virtual image — the principle behind shaving mirrors.

4. Q4 of 6Medium

   When an object is very close to a convex lens, its image looks:

   Ainverted and smallBthe same sizeCerect and enlargedDinvisible
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   Answer: erect and enlarged

   Explanation: When an object sits within a convex lens's focal length, the lens forms an erect, enlarged virtual image — the magnifying-glass effect.

5. Q5 of 6Hard

   A ray hits a mirror and the angle between the incident and reflected rays is 80°. The angle of incidence is:

   A40°B80°C20°D160°
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   Answer: 40°

   Explanation: The angle of incidence always equals the angle of reflection, so the two equal angles together span 80°, making each one 40°.

6. Q6 of 6Hard

   You stand 2 m from a plane mirror. Your image appears to be:

   A4 m behind the mirrorB1 m behind the mirrorC2 m behind the mirrorDon the mirror
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   Answer: 2 m behind the mirror

   Explanation: A plane mirror places the image as far behind the mirror as the object is in front, so standing 2 m away puts the image 2 m behind the mirror.

Light: Mirrors and Lenses notes: key concepts (Class 8 Science)

This chapter is about how mirrors and lenses form images of objects using light. Reflection obeys two laws — the angle of incidence equals the angle of reflection, and the incident ray, reflected ray and normal lie in one plane. A plane mirror forms an erect, same-size, virtual and laterally inverted image. Spherical mirrors are concave (converging — a magnified erect image when the object is close, used in torches and shaving mirrors) or convex (always erect and diminished with a wide view, used as rear-view mirrors). Lenses, which let light pass through and refract it, are convex (a magnifying glass) or concave (always erect and diminished).

Reflection

The bouncing back of light from a surface; it lets us see non-luminous objects by the light they reflect into our eyes.

Laws of reflection

First, the angle of incidence equals the angle of reflection; second, the incident ray, the reflected ray and the normal all lie in the same plane. They hold for all mirrors.

Normal and angles

The normal is the perpendicular at the point where the ray strikes; the angle of incidence and angle of reflection are both measured from this normal.

Plane mirror image

A plane mirror forms an erect, same-size, virtual image, as far behind the mirror as the object is in front, with left and right swapped (lateral inversion).

Spherical mirrors

Curved mirrors — concave surfaces curve inwards and convex surfaces curve outwards; both show lateral inversion.

Concave mirror

A converging mirror that forms a magnified, erect image when the object is close, and can focus parallel sunlight to a hot point — used in torches, headlights and shaving mirrors.

Convex mirror

A diverging mirror that always forms an erect, diminished image and gives a wide field of view — used as rear-view and security mirrors.

Convex lens

A lens thicker in the middle that converges light; used as a magnifying glass. A nearby object looks erect and enlarged, while a far object gives an inverted image.

Concave lens

A lens thicker at the edges that diverges light and always forms an erect, diminished image.

Refraction through lenses

Unlike mirrors, lenses let light pass through and bend (refract) it, which is how they form images.

Regular vs diffuse reflection

A smooth surface reflects light regularly to give a clear image, while a rough surface scatters it (diffuse reflection) so no clear image forms.