A 5.0 cm real object is placed at a distance of 5.0 cm from a concave mirror of focal length 10cm?

Question

Find the size of the image.

A. 5 cm

B. 10 cm

C. 17 cm

D. 20 cm

I put this question up before and no one answered. I would appreciate it if somebody helped me out with this. I'm almost finished this subject! I just need a few more answers! Thanks!

Answer 1

Hello there darkassassin,

What a strange name you have!

size object/size image=distance oboject/distance image

or si/so=di/do

You have

so=5cm

do=5cm

and

focal lenght=10 cm

1/do+1/di=1/f

1/5+1/di=1/10

1/di=1/10+2/10

1/di=-1/10

distance of image is -10cm  (behind mirror)

Now do a cross product of: si/so=di/do

si=di/do*so

si=10/5*5/1=50/5=10

10cm, which would be B

Goodby!