CBSE Class 10 - Physics - Reflection of Light By Plane and Spherical Mirrors (V Short Q and A)

Reflection of Light By Plane and Spherical Mirrors

Laughing Mirrors use combination of Spherical Mirrors and Plane Mirrors.
Is this image real or virtual?

Very Short Question Answers (Based on NCERT Chapter)

Q1: What is the position of the object, when we get a diminished image with a concave mirror?

Answer: Beyond C (centre of curvature)

Q2: What are Marginal rays?

Answer: The rays which strike the mirror surface near the periphery are called marginal rays.

Q3: What type of rear mirrors are used by drivers in automobiles?

Answer: Convex mirrors

Q4: What is the relation between the radius of curvature (R) and focal length (f) of a concave mirror?

Answer: R = 2f

Q5: What is a focal length in case of spherical mirrors?

Answer: It is the distance between focal length and focus.

Q6: An object is moving with a speed v towards a plane mirror, what is the speed of the image?

Answer: 2v.

Q7: What term we use to define the geometric centre of concave or convex mirror?

Answer: Pole

Q8:  What type of images are formed by a concave mirror?

Answer: Both virtual and real.

Q9: What types of mirrors are used in headlights of vehicles?

Answer: concave mirrors

Q10: According to sign conventions, the Radius of curvature of concave mirror is considered as +ve or -ve?

Answer: -ve

Q11: What type of images cannot be taken on screen?

Answer: Virtual images

Q12: Can camera capture virtual images?

Answer: Yes

Q12: If value of magnification is 1, what will be relation between image and the object?

Answer: Size of image equals to size of the object.

Q13: Why does image appear thin or bulging in spherical mirrors?

Answer: In spherical mirrors, light ray converge or diverge upon reflection, hence appearing thin or bulged.

Q14: What is the magnification of a plane mirror?

Answer: 1

Q15: What type of mirrors are used by dentists or ENT specialists?

Answer: concave mirrors.

Q16: If magnification m > 1, is the image formed enlarged or reduced?

Answer: enlarged

Q17: What types of mirrors are used in saloons?

Answer: Plane mirrors

Q18:  If magnification m < 0, is the image formed erect or inverted?

Answer: inverted.

Q19: Where will the images of stars or the moon be formed for a concave mirror?

Answer: At focus of mirror. Image will be point sized.

Q20: Find the focal length of a convex mirror whose radius of curvature is 32 cm?

Answer:  R = 32cm. f = R/2 = 32/2 = 16 cm

Q21: Name a mirror that can give an erect and enlarged image of an object.

Answer: Concave mirror

Q22: No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be _____?

Answer: either plane or convex mirror.

Q23: How many images do we see between two parallel mirrors?

Answer: Infinite

Q24: If the image is not there where light goes after reflection, such image is called as?

Answer: Virtual image

Q25: Will the value of magnification of a rear mirror used in car is positive or negative?

Answer: Positive (+m < 1) because image needs to be erect.

Q26: What is the focal length of a plane mirror? (zero or infinite)

Answer: Infinite

Q27: A light ray parallel to principal axis falls on a concave mirror and bends towards focus. Will angle of incidence be equal to angle of reflection?

Answer: Yes

Q28 (HOTS): Can a convex mirror or plane mirror form a real image?

Answer: Usually convex mirror or plane mirror forms virtual images. But it can form a real image, if the object is virtual, i.e., if the light rays converging at a point behind a plane mirror (or a convex mirror) are reflected to a point on a screen placed in front of the mirror, then a real image will be formed. eg Throw a torch at the plane mirror.