Question

17. An object is placed at a distance of 30
cm from a concave mirror of focal length
15cm. the image will be
a) real and of same size
b) real and magnified
c) real and diminished
d) virtual and magnified​

Answer 1

Answer:

d. virtual and magnified

Explanation:

Given = object distance,u = -30cm

Focal length = -15cm

using mirror formula,

1/f = 1/v+1/u

1/-15=1/v+1/-30

1/-15+1/30=1/v

2 - 1/-30 = 1/v

1/-30=1/v

v = -90cm

using the formula for linear magnification,

Linear magnification = -v/u

= -90/-30

= 3

Hence from the above calculation we can see that the magnification is positive hence the image does will be virtual and erect.