An object is 30 cm in front of a converging lens of focal length 10 cm.The image is:
A)real and larger than the object
B)real and the same size than the object
C)real and smaller than the object
D)virtual and the same size than the object
E)virtual and smaller than the object

Question

Quizplus · Accepted Answer

Since the object is placed beyond the focal length of the converging lens, the image will be real, inverted and smaller than the object. The image distance can be calculated using the lens formula as:

1/f = 1/do + 1/di

where f is the focal length, do is the object distance (negative in this case as it is in front of the lens), and di is the image distance.

On substituting the given values, we get:

1/10 = 1/-30 + 1/di

Solving for di, we get di = -15 cm.

Since the image distance is negative, the image is formed on the same side as the object (i.e., left side) and hence, the image is real. Also, since the magnification (m) is given by:

m = -di/do

(where negative sign denotes inversion), we get:

m = -(-15)/(-30) = 0.5

which indicates that the image is smaller than the object. Therefore, the correct option is C) real and smaller than the object.

An Object Is 30 Cm in Front of a Converging