A 2.0-cm-tall candle flame is 2.0 m from a wall. You happen to have a lens with

ID: 1784420 • Letter: A

Question

A 2.0-cm-tall candle flame is 2.0 m from a wall. You happen to have a lens with a focal length of 42 cm .

A: How many places can you put the lens to form a well-focused image of the candle flame on the wall?

Number of places = 2 **Correct**

B: What are the distance between the candle and the lens for each location?

x1,x2 = 60 cm , 140 cm **Correct**

QUESTION:

C: For each location, what is the height of the image? (Express your answer using two significant figures separated by a comma.)

h'1, h'2 = _______ cm

D: For each location, what is the orientation of the image?

both are upright first is upright, second is inverted first is inverted, second is upright both are inverted

Apply lens equation

1/f = 1/p + 1/q

1/42 = 1/60 + 1/q

q = 140 cm

from the magnification equaiton

m = -q/p

hi/ ho = -q/p

h1'= hi = ho ( - q/p)

= 2 cm ( - 140/ 60)

= -4.66 cm

m = -q/p = -140/60 = -2.33

Apply lens equation

1/f = 1/p + 1/q

1/42 = 1/140 + 1/q

q = 60cm

from the magnification equaiton

m = -q/p

hi/ ho = -q/p

hi = ho ( - q/p)

= 2 cm ( - 60/ 140)

h2' = hi = -0.857 cm

m = -60/140 = -0.428

in both cases magnfication of negative so both are inverted

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