Question

a concave mirror produces a real image of magnification 1/2 when an object is placed at a distance of 50 cm from it where should be the object be placed so that a virtual image of double the size is formed by the mirror​

Answer 1

Answer:

Initial obj. dist = -60(real object)

". magnification (m) = -1/2 (as both obj and image are real)

We know , m= -f/(u-f) [f=focal length]

f= -20cm

Now , obj dist = u'

magnification(m')=2 (as image is virtual of real object)

f=-20 cm

We know , m= -f/(u'-f)

2=20/(u'+20)

u'=-10cm

Hence , the obj should at a distance of 10 cm in front of the mirror.