logo

Ask Questions, Get Answers

 
X
 Search
Want to ask us a question? Click here
Browse Questions
Ad
0 votes

An object of length $2.5\;cm$ is placed at a $1.5\; f$ from a concave mirror where f is magnitude of focal length of mirror. The length of object is perpendicular to principal axis . Then which of following will be correct . (i) image is 5 cm long (ii) image is 10 cm long (iii) image is inverted (iv)image is erect

(a)both (i) and (iv)

(b)both (i) and (iii)

(c) both (ii) and (iii)

(d) both (ii) and (iv)  

Can you answer this question?
 
 

1 Answer

0 votes
Focal length $F= -f$
and $u=-1.5\;f$
$\large\frac{1}{u}+\frac{1}{v}=\frac{1}{F}$
$\large\frac{1}{-1.5 \;f}+\frac{1}{v}=\frac{-1}{f}$
$\large\frac{1}{v}=\frac{1}{1.5 f}-\frac{1}{f}$
$\qquad= -\large\frac{-1}{3f}$
$v= -3 f$
Now $m =\large\frac{-v}{u}=\frac{-3 f}{1.5 \;f}$$=-2$
or $\large\frac{h_2}{h}$$=-2$
or $h_2=-2 h_1=-5 cm$
the image is 5 cm long.
The minus sign shows that it is inverted.
Hence c is the correct answer.

 

answered Feb 11, 2014 by meena.p
edited Jul 21, 2014 by thagee.vedartham
 

Related questions

Ask Question
student study plans
x
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App
...