Spherical Mirrors — Homi Bhabha Class 9 Physics MCQs with Solutions
Free Homi Bhabha Class 9 Physics Spherical Mirrors MCQs with step-by-step solutions (9 questions). Part of Light & Optics. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Spherical Mirrors · medium · theory
A concave mirror is used as a shaving/make-up mirror because, when the face is close to it, it forms an image that is:
A. real and inverted
B. erect and magnified ✓ Correct
C. inverted and diminished
D. the same size
Solution: For an object within its focus, a concave mirror gives an erect, magnified (virtual) image.
Q2 — Spherical Mirrors · medium · theory
A convex mirror is preferred as a rear-view mirror in vehicles because it:
A. gives an inverted image
B. shows a narrow field of view
C. gives a magnified image
D. gives an erect, diminished image and a wider field of view ✓ Correct
Solution: A convex mirror always forms an erect, smaller image and covers a wider area behind the vehicle.
Q3 — Spherical Mirrors · medium · numerical
The focal length of a spherical mirror of radius of curvature 20 cm is:
A. 5 cm
B. 40 cm
C. 10 cm ✓ Correct
D. 20 cm
Solution: Focal length $= \dfrac{R}{2} = \dfrac{20}{2} = 10$ cm.
Q4 — Spherical Mirrors · hard · numerical
A concave mirror has a focal length of 15 cm. Its radius of curvature is:
A. 7.5 cm
B. 30 cm ✓ Correct
C. 45 cm
D. 15 cm
Solution: Radius of curvature $R = 2f = 2 \times 15 = 30$ cm.
Q5 — Spherical Mirrors · hard · theory
When an object is placed beyond the centre of curvature of a concave mirror, the image formed is:
A. real, inverted and diminished ✓ Correct
B. virtual and diminished
C. real, erect and magnified
D. virtual, erect and magnified
Solution: For an object beyond C, a concave mirror forms a real, inverted, diminished image between F and C.
Q6 — Spherical Mirrors · easy · theory
For a spherical mirror, the focal length f is related to its radius of curvature R by which relation?
A. f = R
B. f = R/4
C. f = R/2 ✓ Correct
D. f = 2R
Solution: The focus of a spherical mirror lies midway between the pole and the centre of curvature, so the focal length is half the radius of curvature: f = R/2.
Q7 — Spherical Mirrors · medium · numerical
A concave mirror has a radius of curvature of 20 cm. What is its focal length?
A. 40 cm
B. 10 cm ✓ Correct
C. 20 cm
D. 5 cm
Solution: Focal length f = R/2 = 20/2 = 10 cm. Answering 40 cm mistakenly doubles the radius instead of halving it.
Q8 — Spherical Mirrors · hard · theory
An object is placed exactly at the centre of curvature of a concave mirror. The image formed is:
A. Virtual, erect and magnified
B. Real, inverted and the same size, located at the centre of curvature ✓ Correct
C. Real, inverted and diminished, located beyond C
D. Virtual, erect and diminished
Solution: When an object sits at the centre of curvature C of a concave mirror, the rays return to form a real, inverted image of the same size, also at C. This is the special same-size case used in ray-diagram rules.
Q9 — Spherical Mirrors · hard · numerical
An object is placed 30 cm in front of a concave mirror whose focal length is 15 cm. Using the mirror formula, where is the image formed?
A. 10 cm in front of the mirror
B. 60 cm in front of the mirror
C. 30 cm in front of the mirror ✓ Correct
D. 15 cm behind the mirror
Solution: The object is at 2f (30 = 2 x 15), so the image also forms at 2f. Using 1/v + 1/u = 1/f with u = -30 and f = -15 gives 1/v = -1/15 + 1/30 = -1/30, so v = -30 cm, i.e. 30 cm in front of the mirror, real and inverted.