Question

Write two characteristics of image formed when an object is placed between

the optical centre and focus of a thin convex lens. Draw the graph showing

variation of image distance v with object distance u in this case.​

Answer 1

Answer:

Two characteristics- virtual and enlarged image and same side of

object.

Explanation:

Two characteristics- virtual and enlarged image and same side of

object.

As u and v both negative, we get 1/v=1/u-1/f

Interpret y=mx+c ,plot of the graph .

Answer 2

Answer:

Two characteristic:

1. Virtual image will be formed on the same side of object.

2. Image formed will be enlarged.

Explanation:

1. As you can see from the diagram when the object is placed in between optical center and focus of the lens image thus formed is virtual and magnified.
2. we can verify is use the lens equation: consider object is placed at f/2 distance from the optical center (just like in above diagram)

• Using lens formula, $\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$
• $\frac{1}{v} - \frac{1}{-f/2} = \frac{1}{f}$
• $\frac{1}{v} + \frac{2}{f} = \frac{1}{f}$

• $\frac{1}{v} = \frac{1}{f} - \frac{2}{f}$
• $\frac{1}{v} = \frac{-1}{f}$
• $v=-f$
• this means that the image formed is on the same side as the object (virtual).
• Magnification = $\frac{-v}{u} = -\frac{-f}{\frac{f}{2}} = 2$ , which mean image is magnified.