Following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Q.1. Assertion(A) : The centre of curvature is not a part of the mirror. It lies outside its reflecting surface.
Reason (R) : The reflecting surface of a spherical mirror forms a part of a sphere. This sphere has a centre.
Q.2. Assertion (A) : A ray passing through the centre of curvature of a concave mirror after reflection, is reflected back along the same path.
Reason (R) : The incident rays fall on the mirror along the normal to the reflecting surface.
Q.3. Assertion (A) : Light does not travel in the same direction in all the media.
Reason (R) : The speed of light does not change as it enters from one transparent medium to another.
Q.4. Assertion(A) : The emergent ray is parallel to the direction of the incident ray.
Reason (R) : The extent of bending of the ray of light at the opposite parallel faces (air- glass interface and glass-air interface) of the rectangular glass slab is equal and opposite.
Q.5. Assertion(A) : A ray of light travelling from a rarer medium to a denser medium slows down and bends away from the normal. When it travels from a denser medium to a rarer medium, it speeds up and bends towards the normal.
Reason (R) : The speed of light is higher in a rarer medium than a denser medium.
Q.6. Assertion(A): The mirrors used in search lights are concave spherical.
Reason (R) : In concave spherical mirror the image formed is always virtual.
Q.7. Assertion(A) : Light travels faster in glass than in air.
Reason (R) : Glass is denser than air.
Q.8. Assertion(A) : For observing traffic at back, the driver mirror is convex mirror.
Reason (R) : A convex mirror has much larger field of view than a plane mirror.
Q.9. Assertion(A) : Mirror formula can be applied to a plane mirror.
Reason (R) : A plane mirror is a spherical mirror of infinite focal length.
Q.10. Assertion(A) : It is not possible to see a virtual image by eye.
Reason (R): The rays that seem to emanate from a virtual image do not in fact emanates from the image.
Q.11. Assertion(A) : When the object moves with a velocity 2 m/s, its image in the plane mirror moves with a velocity of 4 m/s.
Reason (R) : The image formed by a plane mirror is as far behind the mirror as the object is in front of it.
Q.12. Assertion(A) : The height of an object is always considered positive.
Reason (R) : An object is always placed above the principal axis in this upward direction.
Q.13. Assertion(A) : Concave mirrors are used as make-up mirrors.
Reason (R) : When the face is held within the focus of a concave mirror, then a diminished image of the face is seen in the concave mirror.
Q.14. Assertion(A) : Refractive index has no units.
Reason (R) : The refractive index is a ratio of two similar quantities.
Q.15. Assertion(A) : The formula connecting u, v and f for a spherical mirror is valid in all situations for all spherical mirrors for all positions of the object.
Reason (R) : Laws of reflection are strictly valid for plane surfaces.
Q.16. Assertion(A): A person cannot see his image in a concave mirror, unless, he is standing beyond the center of curvature of the mirror.
Reason (R) : In a concave mirror, image formed is real provided the object is situated beyond its focus.
Q.17. Assertion(A): Virtual images are always erect.
Reason (R) : Virtual images are formed by diverging lenses only.