You are designing a concave mirror to project text onto a screen. The text consists of letters 6.00 mm tall, and the image of the letters should be 36.0 cm tall. The screen must be 8.00 m from the vertex of the mirror. How far from the vertex of the mirror should the text be placed, and what should the radius of the mirror be?
Solution
As we know that;
= ho = 6 mm = 0.6 cm
= hi = 36 cm
= di = 800 cm
So,
= do = di * ( ho/hi)
= do = 800 * ( 0.6/36)
= do = 13.3 cm
Then,
Using the lens formula,
= 1/f = 1/di + 1/do
= 1/f = 1/13.3 + 1/800
= f = 13.1 cm
So,
= r = 2*f
= 2*13.1cm
= 26.2 cm
.
Basic Civil Engineering first year Notes- Chapter 4 Building.pptx
You are designing a concave mirror to project text onto a screen- The (1).docx
1. You are designing a concave mirror to project text onto a screen. The text consists of letters 6.00
mm tall, and the image of the letters should be 36.0 cm tall. The screen must be 8.00 m from the
vertex of the mirror. How far from the vertex of the mirror should the text be placed, and what
should the radius of the mirror be?
Solution
As we know that;
= ho = 6 mm = 0.6 cm
= hi = 36 cm
= di = 800 cm
So,
= do = di * ( ho/hi)
= do = 800 * ( 0.6/36)
= do = 13.3 cm
Then,
Using the lens formula,
= 1/f = 1/di + 1/do
= 1/f = 1/13.3 + 1/800
= f = 13.1 cm
So,
= r = 2*f
