e) Onity two of the aboue stanemenns ane true 18. If a student stands im front o

Question

e) Onity two of the aboue stanemenns ane true 18. If a student stands im front of a concaue mimor, exacty at its focal pomt a) he vwill see his image at is same heght b) he will see his image, and ite will appear smaler c) he will see his image and he will appear larger d) he won't see his image because it's focused at a difieret e) he won't see his image because thene is mone distance 19. If the radius of curvature of the concave mimar is the focal length is s t. the focal lengt is a) /2. b) r c) 2r d) cannot be denermined from the infomation gie 20. What principle is responsible for ahermating light and dark bands whem light passes through two or more narrow slits? a) refraction b) polarization c) diffraction d) interference

Explanation / Answer

18) for concave mirror

1/f = 1/do + 1/di

given that do = f

then 1/f = 1/f + 1/di

1/di = 0

di = infinite

since the inage distance is at infinite So he won't see his image

So the answer is e) he won's see his image because there is none

19) in case of any mirror

focal length = 2*Radius of curvature

f = 2*r

so the answer is C) 2r

20) As we see in case of Young's double slit experiment ,,Interference is responsible for the alternationg bright and dark bands

So the answer is d) interference

9) voltmeter must be connected in parallel and ammeter must be conneted in series with any element

So the answers are A) Voltmeter should be connected in parallel to the resistor

and d) Ammeter should be connected in series to the resistor

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