Reflection of Light By Plane and Spherical Mirrors
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| 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.
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