You’re using a concave lens with f = -5.4 cm to read 4.7 mm high newspaper type.

ID: 1513559 • Letter: Y

Question

Part A

How high do the type characters appear if you hold the lens 1.0 cm from the newspaper?

4.0mm (Correct)

Part B

How high do the type characters appear if you hold the lens 3.6 cm from the newspaper?

Express your answer to two significant figures and include the appropriate units.

Part C

How high do the type characters appear if you hold the lens 12 cm from the newspaper?

Express your answer to two significant figures and include the appropriate units.

A) f = - 5.4 cm

Applying lens equation,

do = 1cm

1/f = 1/do + 1/di

1/-5.4 = 1/1 + 1/di

di =- 0.844 cm

m = hi./ ho = -di/do

hi / 4.7 = - (-0.844) / (1)

hi = 3.97 mm

B) 1/-5.4 = 1/3.6 + 1/di

di = - 2.16 cm

hi / 4.7 = - (-2.16 / (3.6)

hi =2.82 mm

c) 1/-5.4 = 1/12 + 1/di

di = - 3.72 cm

hi / 4.7 = - (-3.72 / 12)

hi =1.46 mm

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