Images Formed by Convex Lenses

Maharashtra State Board: Class 10

Rules for Image Formation by a Convex Lens

Rule No.	Description	Diagram
Rule 1	When the incident ray is parallel to the principal axis, the refracted ray passes through the principal focus (F₂).
Rule 2	When the incident ray passes through the principal focus (F₁), the refracted ray becomes parallel to the principal axis.
Rule 3	When the incident ray passes through the optical centre (O) of the lens, it does not change direction.

Maharashtra State Board: Class 10
CISCE: Class 10

S. No.	Position of the Object	Position of the Image	Size of the Image	Nature of the Image
1	At infinity	At focus (F₂)	Point image	Real and inverted
2	Beyond (2F₁)	Between (F₂) and (2F₂)	Smaller	Real and inverted
3	At (2F₁)	At (2F₂)	Same size	Real and inverted
4	Between (F₁) and (2F₁)	Beyond (2F₂)	Larger	Real and inverted
5	At focus (F₁)	At infinity	Very large	Real and inverted
6	Between (F₁) and O	On the same side of the lens as the object	Very large	Virtual and erect

Maharashtra State Board: Class 10

1. Aim: To study the formation of images by a convex lens at different object positions and observe the nature, size, and position of the image.

2. Requirements: convex lens, screen, meter scale, lens stand, candle, and chalk

3. Procedure

Draw a straight line on a table and place the convex lens at the centre (O).
Place a screen on one side and adjust it to form a clear image of a distant object, marking its focus (F₁).
Measure the distance O to F₁ and mark 2F₁ at twice this distance. Repeat for F₂ and 2F₂ on the other side.
Place a burning candle beyond 2F₁ and adjust the screen to obtain a clear image. Record its position, size, and nature.
Repeat the experiment by placing the candle at different positions: beyond 2F₁, at 2F₁, between 2F₁ and F₁, at F₁, and between F₁ and O.
Observe and record the image characteristics for each case.

4. Conclusion

When the object is placed beyond 2F₁, the image is between F₂ and 2F₂, real, inverted, and smaller.
If placed at 2F₁, the image is same-sized, real, and inverted at 2F₂.
When placed between 2F₁ and F₁, the image is beyond 2F₂, real, inverted, and magnified.
At F₁, the image is at infinity, highly magnified, real, and inverted.
If placed between F₁ and O, the image is virtual, erect, and magnified on the same side as the object.

Maharashtra State Board: Class 10

S. No.	Position of the Object	Position of the Image	Size of the Image	Nature of the Image
1	At infinity	At focus F₂	Point image	Real and inverted
2	Beyond 2F₁	Between F₂ and 2F₂	Smaller	Real and inverted
3	At 2F₁	At 2F₂	Same size	Real and inverted
4	Between F₁ and 2F₁	Beyond 2F₂	Larger	Real and inverted
5	At focus F₁	At infinity	Very large	Real and inverted
6	Between F₁ and O	On the same side of the lens as the object	Very large	Virtual and erect