IIT JEE , AIEEE Forum - Physics , Optics - Mirrors-simple reasoning question

learner

I was sitting idly when this occured to me-all rearview mirrors have a message at the bottom:

"Objects in the mirror are closer than they appear"

Now,is it true that if a person is standing at a distance 'x ' from the mirror, his image is formed at a distance greater than x?

If not,how do you explain the statement?

If yes,how does it concur with mirror formula?

answer tomorrow

rida

"appear "

nice question

harsha_27

Yes.It means to say if a person is standing at a distance 'x ' from the mirror, his image is formed at a distance greater than x.

zorro

DUDE, u hav read wrongly...

objects appear in the mirror are more closer than they actually are..

because rearview mirror uses convex mirror ,

and we know that in case of convex mirror , object can be placed anywhere but its image always be vrtual ,errect , diminished and between centre of mirror and focus on other side...

so, image is formed at a distance less than x..

note: here I discussed abt real object.

learner

@Harsha-sorry dude..wrong answer

Dear Zorro,I've not read wrongly..if you think I'm dyslexic and can't understand a simple sentence like that,kindly check a mirror yourself.The same thing will be written.

But your reasoning is correct.According to mirror formula,image is formed at a distance less than x.

Perfectly true..thanks for posting all that.You deserve your rate.

But then are mirror makers all wrong????Why would they write something like that on the mirror??

Put a little thought,you'll definitely get it..

Answer postponed by a day

cheers :-)

spideyunlimited

"Objects in the mirror are closer than they appear"

The image of the objects are formed further from the pole than the objects themselves.
Now looking at the image distance from the pole of the mirror.. we imagine the actual object to be the same distance from the pole... so we seem to think it is further behind... whereas the object is actually closer than the apparent distance it seems to our minds.

learner

But image ISN'T formed further than the object!!

See,1/f=1/u+1/v

so f=uv/(u+v)

u is negative,v is positive for convex mirror,

so,f= -|uv| / (v-|u|)

but f should be postivie for convex mirror..

so,from this equation,magnitude of v should be less than that of u..

otherwise you'll get -ve f...

spideyunlimited

ok ill b back with the answer . dont give the answer today :)
gotta go :)

learner

@Hemanth - Is there a mistake two posts above?

spideyunlimited

http://dza.colorado.edu/~class/Phys4510/Notes/Convex%20Mirror.htm

learner

Woah...thanks spidey..that diagram is so apt!!!!

.

Ok here's the answer..

As correctly stated by Zorro and by the proof I gave,the image is surely formed nearer than the object.

In other words,u>v..

Now an optical illusion takes place..we all know that the convex mirror provides a large field of view and DIMINISHES objects..

And we consider a small object to be distant....so we FEEL the image is formed very far away..

Hence the note on rearview mirrors..

Thanks

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