A diverging lens of focal length 30cm produces an image 20cm from the lens. Determine the object distance
-
A.
10cm -
B.
12cm -
C.
50cm -
D.
60cm
Correct Answer: Option D
Explanation
Lens formula:
(frac{1}{f} = frac{1}{d_o} + frac{1}{d_i})
where f, d(_o) and d(_i) are the focal length, object distance and image distance respectively.
⇒ (frac{1}{30} = frac{1}{d_o} + frac{1}{20})
(frac{1}{d_o} = frac{1}{30} – frac{1}{20})
(frac{1}{d_o} = frac{-1}{60})
(d_o = – 60 cm)
The object distance = 60cm.