Question

Draw the ray diagram of image formed by convex lens having focal length 2cm. If lighting candle is placed 4cm from the lens, calculate the magnification of the lens.​

Answer 1

Answer:

In the above diagram,L  

1

​

 and L  

2

​

 are two convex lenses, O be the point object and I  

1

​

 and I  

2

​

 are the images obtained by the lens L  

1

​

 and L  

2

​

.

Let P  

1

​

 and P  

2

​

 are the power of the lenses, and f  

1

​

andf  

2

​

 are the focus length of the two lenses then,

f  

1

​

 

1

​

=  

v  

1

​

 

1

​

−  

u

1

​

−−−−−−−−−−(1)

f  

2

​

 

1

​

=  

v

1

​

−  

v  

1

​

 

1

​

−−−−−−−−−−(2)

By adding the equation (1) and (2)

v

1

​

−  

u

1

​

=  

f  

1

​

 

1

​

+  

f  

2

​

 

1

​

 

So, We know that ,

P=  

f

1

​

 

So P=  

f  

1

​

 

1

​

+  

f  

2

​

 

1

​

 

Then, P=P  

1

​

+P  

2

​

.

Explanation: