Optics part (2)

11. In driving a car which type of mirror would you like to use for observing traffic at your back ? [U.P.P.C.S.(pre) 1991, Uttarakhand P.C.S.(PRE) 2005]

(a) concave mirror
(b) spherical mirror
(c) convex mirror
(d) plain mirror

Correct Answer: (c) convex mirror

Solution:A convex mirror gives a much wider field of view of the traffic at your back then a plain mirror of the same size. It always forms an erect and diminished image and they also have a wider field of view as they are curved outwards.

12. Which one of the following types of the mirror is used to see the traffic behind the car ? [U.P.P.C.S. (pre) 2015]

(a) convex mirror
(b) concave mirror
(c) plane mirror
(d) spherical mirror

Correct Answer: (a) convex mirror

Solution:A convex mirror gives a much wider field of view of the traffic at your back then a plain mirror of the same size. It always forms an erect and diminished image and they also have a wider field of view as they are curved outwards.

13. Which mirror is used as a rear view mirror in vehicles ? [U.P.P.C.S. (pre) 2011, U.P.P.C.S. (mains) 2010]

(a) plain
(b) convex
(c) concave
(d) cylindrical

Correct Answer: (b) convex

Solution:A convex mirror gives a much wider field of view of the traffic at your back then a plain mirror of the same size. It always forms an erect and diminished image and they also have a wider field of view as they are curved outwards.

14. The image formed by concave mirror is real, inverted and of the same size as that of the object. The position of the object should be : [B.P.S.C. (Pre) 2023]

(a) at the focus
(b) at the centre of curvature
(c) between the focus and centre of curvature
(d) beyond the centre of curvature

Correct Answer: (b) at the centre of curvature

Solution:If an object is placed at the centre of curvature of a concave mirror, then the image formed is real, inverted and of the same size as that of the object. The image formed is not magnified.

15. A person standing in front of a mirror finds his image larger than himself. This implies that the mirror is: [67th B.P.S.C.(PRE) 2022]

Correct Answer: (a) concave

Solution:A person standing in front of a mirror finds his image larger than himself implies that the mirror is concave. A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the centre of the sphere, is called a concave mirror. Concave mirrors are commonly used in torches, search-lights and vehicles' headlights to get powerful parallel beams of light. They are often used as shaving mirrors to see a large image of the face. Dentists use concave mirrors to see large images of the teeth of patients.

16. For shaving one uses - [43rd B.P.S.C. (PRE) 1999]

(a) concave mirror
(b) plain mirror
(c) convex mirror
(d) none of these

Correct Answer: (a) concave mirror

Solution:People use a concave mirror for shaving because when a man standing between the principle focus and a pole of a concave mirror he sees as enlarged the erect and virtual image of his face. This is the reason why a concave mirror of a large focal length is used for shaving.

17. The mirror which is used in searchlights is - [U.P.P.C.S.(mains) 2009]

(a) concave mirror
(b) convex mirror
(c) simple mirror
(d) none of these

Correct Answer: (a) concave mirror

Solution:concave mirror is used in the headlights of cars and in searchlight .A light is placed at the focus of concave lens can form a parallel beam and is used in car headlight and searchlights.

18. The mirror used by a dentist to examine the teeth of the patient is [U.P.P.C.S. (pre) 2013, U.P.P.C.S. (pre) (re.exam) 2015]

(a) concave
(b) convex
(c) plane
(d) cylindrical

Correct Answer: (a) concave

Solution:concave mirror is used in the headlights of cars and in searchlight .A light is placed at the focus of concave lens can form a parallel beam and is used in car headlight and searchlights.

19. In order to avoid sunlight which of the following colour combination for an umbrella is most appropriate ? [U.P.P.C.S.(pre) 1993]

(a) top black and bottom white
(b) top white and bottom black
(c) only black
(d) only white

Correct Answer: (b) top white and bottom black

Solution:In order to avoid sunlight heat option (b) top of the white and bottom black combination for an umbrella is most appropriate the outer colour will reflect most of the radiation while the black colour inside will absorb anything passing through the outer layer.

20. The image formed by astronomical telescope is - [U.P.P.C.S.(MAINS) 2013]

(a) virtual and diminished
(b) virtual and magnified
(c) real and diminished
(d) real and magnified

Correct Answer: (b) virtual and magnified

Solution:Astronomical telescope consists of two convex lenses: Objective and Eyepiece.

The final image formed by the astronomical telescope is inverted, virtual and highly magnified.

Optics part (2)

11. In driving a car which type of mirror would you like to use for observing traffic at your back ? [U.P.P.C.S.(pre) 1991, Uttarakhand P.C.S.(PRE) 2005]

12. Which one of the following types of the mirror is used to see the traffic behind the car ? [U.P.P.C.S. (pre) 2015]

13. Which mirror is used as a rear view mirror in vehicles ? [U.P.P.C.S. (pre) 2011, U.P.P.C.S. (mains) 2010]

14. The image formed by concave mirror is real, inverted and of the same size as that of the object. The position of the object should be : [B.P.S.C. (Pre) 2023]

15. A person standing in front of a mirror finds his image larger than himself. This implies that the mirror is: [67th B.P.S.C.(PRE) 2022]

16. For shaving one uses - [43rd B.P.S.C. (PRE) 1999]

17. The mirror which is used in searchlights is - [U.P.P.C.S.(mains) 2009]

18. The mirror used by a dentist to examine the teeth of the patient is [U.P.P.C.S. (pre) 2013, U.P.P.C.S. (pre) (re.exam) 2015]

19. In order to avoid sunlight which of the following colour combination for an umbrella is most appropriate ? [U.P.P.C.S.(pre) 1993]

20. The image formed by astronomical telescope is - [U.P.P.C.S.(MAINS) 2013]

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