CBSE Class 8 Science Chapter 10 Light Mirrors And Lenses MCQs Set 01

Answer: (B) The image appeared inverted

Explanation:
According to the chapter, when observing the inner side of a spoon which curves inward, the image appears inverted. This happens because the inner surface acts as a concave mirror.

Answer: (C) A hollow glass sphere

Explanation:
The text explicitly states that spherical mirrors are shaped like a part of an imaginary hollow glass sphere, which distinguishes them from plane mirrors.

Answer: (C) A concave mirror

Explanation:
• According to 'A step further' section
• Reflective coating on outer curved surface creates concave mirror
• Coating on inner curved surface creates convex mirror

Answer: (B) Erect and enlarged

Explanation:
The chapter describes that when an object is placed close to a concave mirror, the image is erect but larger than the object in size, meaning it is enlarged.

Answer: (C) The size of the image decreases slightly

Explanation:
In a convex mirror, the image is always erect and smaller than the object. However, the size of the image decreases slightly as the object is moved away from the convex mirror.

Answer: (C) Telescopes

Explanation:
The chapter explicitly mentions that most modern telescopes use reflecting designs with a large concave mirror as the main mirror, and that torches and car headlights also use concave reflectors.

Answer: (B) Angle of incidence is equal to angle of reflection

Explanation:
Activity 10.4 and its results clearly demonstrate through experimentation that the angle of incidence (i) is equal to the angle of reflection (r), which is stated as a fundamental law of reflection.

Answer: (B) They converge and come closer together

Explanation:
Activity 10.6 shows that when multiple parallel beams of light fall upon a concave mirror, the reflected beams converge, meaning they get closer together and come to a point.

Answer: (B) Light concentrated at a point produces sufficient heat to ignite the paper

Explanation:
Activity 10.7 demonstrates that light from the Sun, after reflection from the concave mirror, gets concentrated on a single point, which produces sufficient heat at that point to ignite the paper.

Answer: (B) Curved transparent materials can change how objects appear

Explanation:
The water drop in Activity 10.8 acts like a simple lens. Its curved surface causes the letters underneath to appear different—potentially larger—showing that curved transparent surfaces can refract light and alter the appearance of objects.

Answer: (D) A convex lens is thicker in the middle while a concave lens is thicker at the edges

Explanation:
The chapter defines a convex lens as being thicker at the middle compared to the edges, while a concave lens is thicker at the edges compared to the middle, which is the opposite relationship.

Answer: (C) Erect and diminished

Explanation:
According to Activity 10.9, an object placed behind a concave lens always appears erect and diminished in size, regardless of the distance from which it is viewed.

Answer: (B) Converging lens

Explanation:
The chapter explicitly states that a convex lens is called a converging lens because it converges light beams falling upon it, bringing them together at a point.

Answer: (B) To provide drivers visibility of the other side from both directions and prevent collisions

Explanation:
The text specifically states that convex mirrors provide a much wider area of the road behind and are installed at road intersections or sharp bends to provide drivers from both sides the visibility of the other side and prevent collisions.

Answer: (B) The reflected beam disappears

Explanation:
Activity 10.5 demonstrates that the reflected beam disappears when the sheet is bent because bending creates a new plane that breaks the alignment where the incident ray, normal, and reflected ray must all lie in the same plane.

Answer: (B) Convex mirror

Explanation:
When an object is viewed in a convex mirror, the image always appears erect and smaller than the actual object, which matches Meena's observation of seeing a tiny version of herself.

Answer: (B) Convex mirror

Explanation:
From the side view, a convex mirror's reflecting surface curves outward (bulges), while a concave mirror's surface curves inward. This visual difference is the key to identifying them by their shape alone.

Answer: (B) Its concave shape that curves inward

Explanation:
• Concave mirrors curve inward
• When an object is placed close to a concave mirror, it produces an enlarged, erect image
• This magnification is exactly what dentists need for detailed tooth inspection

Answer: (B) 0 degrees

Explanation:
When a ray travels along the normal, it is perpendicular to the mirror surface. Both the angle of incidence and the angle of reflection would be zero because both are measured from the normal itself.

Answer: (B) The incident ray, normal, and reflected ray no longer existed in the same plane

Explanation:
The second law of reflection states that the incident ray, normal, and reflected ray must all lie in the same plane. Bending the paper creates a new plane, breaking this alignment and making the reflected beam invisible on the bent section.

Answer: (C) It converges parallel light rays to a small point, concentrating heat

Explanation:
Concave mirrors converge (bring together) parallel light rays at a focal point. This concentration of light creates intense heat at that spot, making it ideal for solar concentrators and furnaces.

Answer: (B) You see objects reflected in mirrors but see objects through lenses

Explanation:
Unlike mirrors where you see the reflected image in the mirror surface, lenses are transparent materials that allow light to pass through them, and you observe the object or its image on the other side by looking through the lens.

Answer: (B) Convex lens

Explanation:
The water drop with its curved outer surface acts like a convex lens. Convex lenses are thicker in the middle and cause light to converge, which is why the text appeared enlarged when viewed through the water drop.

Answer: (B) Concave lens always produces smaller images

Explanation:
A concave lens, also called a diverging lens, always produces an erect and diminished (smaller) image regardless of the object's distance from it. In contrast, a convex lens can produce images of varying sizes depending on the distance.

Answer: (B) The curved surface of the concave mirror causes rays to change direction differently at each point

Explanation:
A plane mirror has a flat surface, so all parallel rays reflect to remain parallel. A concave mirror's inward-curving surface causes each ray to reflect at a different angle, resulting in the rays converging toward a focal point rather than remaining parallel.