When an object is placed 20cm from a concave mirror,a real image magnified three times is formed . Find the focal length of the mirror.Where must the ovject be placed to give a virtual image three times the hight of the object?
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When an object is placed 20cm from a concave mirror,a real image magnified three times is formed . Find the focal length of the mirror.Where must the ovject be placed to give a virtual image three times the hight of the object?
Answer
Magnification m = -3
U = -20 cm
m = -v/u ( formula)
-3 = -v/u
U = -20 cm
-3 = -v/(-20)
By calculating you will get the answer as
V = -60 cm
Image is located 60 cm Infront of the mirror
☣ MIRROR FORMULA☣
1/v + 1/u = 1/f
1/(-60) + 1/(-20) = 1/f
By calculating we will get the answer as
F = -15 cm
(2) m = h2 /h1
m = -v/u = 3
V = -3u
☣MIRROR FORMULA☣
Applying again
1/v + 1/u = 1/f
1/(-3u ) + 1/u =1/(-15)
By calculating we will get the answer as
➡️ u = -10 cm ⬅️
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