Question

# A spherical silver Christmas tree ornament, 20 cm in diameter, acts as a mirror. (a) Are...

A spherical silver Christmas tree ornament, 20 cm in diameter, acts as a mirror.

(a) Are the images one sees in it real or virtual, upright or inverted? (Select all that apply.)

-real

-virtual

-upright

-inverted

(b) Find the image height of a man 1.9 m tall, standing 3.4 m from the ornament.

a) Since it is spherical mirror So it is like a convex mirror /

The image is inside the mirror So it is VIRTUAL .

The image in convex mirror is virtual and upright .

VIRTUAL , UPRIGHT .

b) Using mirror equation

1/f =1/v+1/u

1/v=1/f -1/u...1

here f=R/2 since R=20/2 =10 cm So f=10/2 =5 cm , u= -3.4 m=-340 cm ( I am using cartesian sign convention )

Put these value in equation 1

1/v=1/5-(-1/340) =1/5+1/340

1/v=(68+1)/340

v=340/69

v=4.93 cm

magnification

m=h'/h =-v/u

h' =-vh/u

here v=4.93 cm ,u=-340cm , h=1.9 m

h' =-(4.93*1.9)/(-340)

h'=0.02755 m

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