# An object 2cm high is placed at a distance of 16cm from a concave mirror which produces a real image 3cm high. what is focal length of the mirror and position of the image??????

2
by msdiancskalisha

2014-10-24T15:53:50+05:30
Size of the object = h1 = 2 cm
size of the image = h2 = -3 cm
u = obj distance = -16 m

Therefore from formula -v/u = h2 / h1, we have
-v/(-16) = -3/2
v/16 = -3/2
v = -3* 16/2
v = - 24 cm

From mirror formula = 1/v + 1/u = 1/f
=> 1/-24 + 1/-16 = 1/f
=> 1/f = (-2 - 3)/ 48
=> 1/f = -5 / 48
=> f = - 48/5
= > f = - 9.6 cm
can i know which one is correct for sure
f = - 9.6 cm
not -6.4cm??
anywayz thakz a lot ankit
no no... i have corrected my mistake. please recheck my answer.... and welcome
2014-10-24T16:23:51+05:30

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Height of the object, h1 = 2 cm
height of the image, h2 = -3 cm
object distance, u = -16cm
image distance = v

magnification =

From mirror formula

So focal length is 9.6cm and image distance is 24cm(to the left of mirror)
i liked ur way of answering
thanks dude!!
yesss, i appreciate your way of answering....! :)
i appreciate u both cause u btoh are saving me from my physics teacher