Physics
Assertion (A) : Convex mirrors are used as a vigilance mirror.
Reason (R) : Convex mirrors form magnified images.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Reflection of Light
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Answer
Assertion is true but reason is false
Explanation
The assertion is correct: convex mirrors are installed in large showrooms, department stores and at road intersections as vigilance or security mirrors because they provide a wide field of view.
The reason is incorrect: a convex mirror always forms a virtual, erect and diminished image of the object, not a magnified one. The diminished image allows a larger area to be observed in the mirror, which is why convex mirrors are useful for surveillance.
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Related Questions
Assertion (A) : The bottom of a pond appears shallower than its actual depth.
Reason (R) : Light rays from the bottom of the pond bend towards the normal as they pass from water to air.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Assertion (A) : A concave mirror can form both real and virtual images.
Reason (R) : The type of image formed by a concave mirror depends on the position of the object relative to the mirror's focal point.
- Both A and R are true and R is the correct explanation of A
- Both A and R are true and R is not the correct explanation of A
- Assertion is true but reason is false
- Assertion is false but reason is true
Fill in the blanks:
(a) Water is optically …………… than air.
(b) Air is optically …………… than glass.
(c) When a ray of light travels from water to air, it bends …………… the normal.
(d) When a ray of light travels from air to glass, it bends …………… the normal.
(e) Refractive index of water is 4/3, so the apparent depth is …………… of the real depth.
(f) The splitting of white light into its constituent colours is called …………… .
(g) A …………… mirror is obtained on silvering the outer surface of a part of a hollow glass sphere.
(h) Radius of curvature of a spherical mirror is …………… its focal length.
(i) The angle of incidence for a ray of light passing through the centre of curvature of a spherical mirror is …………… .
(j) A …………… mirror always forms a virtual image.
(k) A concave mirror forms a virtual image for an object placed …………… .
Write true or false for each statement:
(a) Water is optically denser than glass.
(b) A ray of light when passes from glass to air, bends towards the normal.
(c) The speed of light is more in glass than in water.
(d) The depth of a pond when seen from above appears to be less.
(e) Light travels at a lower speed in water than in air.
(f) Light travels in the same straight line path while passing through different media.
(g) The angle formed between the normal and the refracted ray is known as the angle of incidence.
(h) At the point of incidence, a line drawn at right angles to the surface, separating the two media, is called the normal.
(i) Image is formed by a mirror due to refraction of light.
(j) Rays of light incident parallel to the principal axis pass through the focus after reflection from a concave mirror.
(k) A convex mirror is used as a shaving mirror.
(l) The focal length of a convex mirror is equal to its radius of curvature.
(m) A concave mirror converges the light rays, but a convex mirror diverges them.
(n) A virtual image formed by a spherical mirror is always erect and situated behind the mirror.