39) When the reflection of an object is seen in a plane mirror, the image is: a.

Question

39) When the reflection of an object is seen in a plane mirror, the image is: a. real and upright. b. virtual and upright. c. real and inverted. d. virtual and inverted. 40) Three flat layers of transparent material are stacked upon one another. The top layer has index of refraction n, the middle has n2, and the bottom one has nts. If n>n2> ns, and if a ray of light strikes the top layer at an angle of incidence & 30, in which layer is the angle of refraction the greatest? a. Once the ray enters the touching layers, the angle of refraction remains constant. b. the top layer c. the middle layer d. the bottom layer 41) If a virtual image is formed 8.00 cm along the principal axis from a convex mirror of focal length-15.0 cm, how far is the object from the mirror? a. 30.0 cm b. 6.00 cm c. 3.00 cm d. 17.1 cm 42) A woman looking in a makeup mirror sees her face at twice its actual size and right-side up. If she is c. 18.6 cnm 22.0 cm from the mirror, what is its focal length? a. 44.0 cm b. 48.3 cm d. 56.0 cm 43) When the reflection of an object is seen in a concave mirror the image: a. will always be enlarged. b. may be either real or virtual c. will always be virtual. d. will always be real.

Explanation / Answer

39] option b is correct. image is vertual and upright, but laterally inverted.

40] option d is correct, by snells law, n sin r = constant, if n is less, r will be more.

41] option d

using mirror formula, 1/u + 1/v = 1/f

1/u =  1/f - 1/v = 1/15 - 1/8 = -0.05833

u = 1/-0.05833 = - 17.1 cm

image distance = 17.1 cm

42] option a is correct,

image distance has to be twice and it is formed other side of the mirror.

By mirror formula, 1/f = 1/u + 1/v = 1/-22 + 1/44 = -1/44 or f = -44 cm

  

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