If a convex lens of focal length 12cm is used t... - JAMB Physics 2008 Question
If a convex lens of focal length 12cm is used to produce a real image four times the size of the object, how far from the lens must the object be placed?
A
10 cm
B
15 cm
C
20 cm
D
25 cm
correct option: b
Magnifications = V/U = 4
∴ V = 4U
1/V + 1/U = 1/f
1/4u + 1/U = 1/12
5/4U = 1/12
4U = 12 x 5 = 60
∴ U = 15 cm
∴ V = 4U
1/V + 1/U = 1/f
1/4u + 1/U = 1/12
5/4U = 1/12
4U = 12 x 5 = 60
∴ U = 15 cm
Please share this, thanks:
Add your answer
No responses