An object is placed 36cm from a converging lens of focal length 24cm.If a real image which is 4cm high is formed, Calculate the height of the object.
-
2.0cm
- 4.0cm
- 6.0cm
- 8.0cm
- 10.0cm
The correct answer is: A
Explanation
F = 24cm , U = -36cm(behind lense)
Applying Lense formula = \(\frac {1}{f} = \frac{1}{v} - \frac{1}{u}\)
\(\frac{1}{v} = \frac{1}{24} - \frac{1}{36} = \frac{1}{72}\)
v = 72cm
but Magnification = \(\frac{V}{U} = \frac{h^i}{h_o}\)
\(\frac{72}{-36} = \frac{-4}{h_o}\) \( h_1\) = -4( real image is negative)
by cross multiplying \(h_1\) = 2cm