# A particle moves towards a concave mirror of focal length 30 cm along its axis and with a constant speed of 4 cm/ sec. What is the speed of its image when the particle is at 90 cm from the mirror? Option 1) 2 cm/ sec Option 2) 8 cm/sec Option 3) 1 cm/sec Option 4) 4 cm/sec

Relation between object and image velocity if object is moving along principal axis -

= -

= -

- wherein

= velocity of light

= velocity of image

= velocity of mirror

= velocity of object w.r.t. mirror

= velocity of image w.r.t. mirror

=

Option 1)

2 cm/ sec

Incorrect

Option 2)

8 cm/sec

Incorrect

Option 3)

1 cm/sec

Correct

Option 4)

4 cm/sec

Incorrect

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