Question

A convex lense whose focal length is 20cm will produce a magnified,erect image when the object is placed at the distance of
a)40cm
b)30cm
c)20cm
d)10cm

Answer 1

@AllTehMaffs

Answer 2

hmmmm......

Answer 3

wait a moment

Answer 4

ok :)

Answer 5

it is not 20!

Answer 6

its is D ..but don't know how ??

Answer 7

it is 10!

Answer 8

It has to be between the focal point and the lens. D, yah.

Answer 9

ok lemme explain by diagram

Answer 10

wait i guess the figure is untidy ..
here is my resource material!
http://www.physicsclassroom.com/class/refrn/u14l5db.cfm

Answer 11

it all is related to the lens conventions..

Answer 12

I'm confused ..Need explanation 'bout this prooblem only :/

Answer 13

ok let me try again!

Answer 14

For a convex lens, The real image - the image on the opposite side of the lens - will always be upside down. To get it not inverted (which is what I think they mean by erect) the image has to be a virtual image. And to do that, the object must be placed inside the focal length.

Answer 15

wait i guess a video would be nice right?

Answer 16

hmm right @croslali and @AllTehMaffs how we find its value by putting lens formula ??

Answer 17

You mean how magnified it would be?

Answer 18

hey hey there is no lens formula for these type of questions it is all based on the diagram

Answer 19

No ..wana know the distance of object from lens ..@AllTehMaffs

Answer 20

http://www.youtube.com/watch?v=c6mLLaqLdvg

Answer 21

link is not working ..

Answer 22

wait lemme try again

Answer 23

http://www.youtube.com/watch?v=c6mLLaqLdvg

Answer 24

there does that work?

Answer 25

nope ;;

Answer 26

@hartnn could you help her this seems both hard and easy at the same time to explain maybe you could help?