What image will be produced if an object is placed on the focal point in front of a concave lens?

When the object is at the focus the image will be formed at infinity.

As the object gets closer and closer to the focal point, the image gets further and further from the mirror. When the object is between the mirror and the focal point the image is behind the mirror (virtual); when the object further from the mirror than the focal point the image is in front of the mirror (real).

At the focal point the image switches from being at $-\infty$ to $+\infty$.This is the nature of parallel lines. A slight deviation from parallel makes the intersection switch from one side to the other.

If you want the image and object to be at the same place on the optical axis, the object should be located at the centre of curvature. The image will be real and inverted and the same size as the object.

Both cases are illustrated in diagrams at The Physics Classroom.

In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation.

Spherical lenses are lenses formed by connecting two spherical transparent surfaces. In general, there are two types of spherical lenses. So, lenses formed by binding two spherical surfaces bulging outward are known as convex lenses, while the lenses formed by binding two spherical surfaces such that they are curved inward are known as concave lenses. This is one of the basic difference between concave and convex lenses.

Convex lenses are also known as converging lenses since the rays converge after falling on the convex lens. The concave lenses are known as diverging lenses, as the rays diverge after falling on the concave lens. In this article, we will learn about image formation by concave and convex lenses.

When a ray strikes concave or convex lenses obliquely at its optical centre, it continues to follow its path.
When a ray, parallel to the principal axis strikes concave or convex lenses, the reflected ray passes through a focus on the principal axis.
When a ray, passing through focus strikes concave or convex lenses, the reflected ray will pass parallel to the principal axis.

- When an object is placed at infinity, the real image is formed at the focus. The size of the image is highly diminished and point size.

- When an object is placed beyond the centre of curvature, the real image is formed between the centre of curvature and focus. The image size will not be the same as the object. It will be diminished in size..

- When an object is at the centre of curvature, the real image is formed at the other centre of curvature. The size of the image is the same as compared to that of the object.

- When an object is placed in between the centre of curvature and focus, the real image is formed behind the centre of curvature. The size of the image is larger than that of the object.

- When an object is placed at the focus, a real image is formed at infinity. The size of the image is much larger than that of the object.

- When an object is placed in between focus and optical centre, a virtual image is formed. The size of the image is larger than that of the object.

- When an object is placed at infinity, a virtual image is formed at the focus. The size of the image is highly diminished and point size.

- When an object is placed at a finite distance from the lens, a virtual image is formed between the optical centre and the focus of the convex lens. The size of the image is smaller than that of the object.

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button
Check your score and answers at the end of the quiz

Visit BYJU’S for all Physics related queries and study materials

0 out of 0 arewrong

0 out of 0 are correct

0 out of 0 are Unattempted

View Quiz Answers and Analysis