What is a Concave Lens?

Academic Physics NCERT Class 7

Diverging Lens or Concave Lens - It is a lens that possesses at least one surface that curves inwards in the middle. In other words, it is thin across the middle and thick at the upper and lower edges, because of which the light that enters the lens, get spread out, or diverge, which results in forming a smaller image. Due to this effect, it is also called a negative lens or a diverging lens.

The image formed by a concave lens is virtual & erect, which means it will appear to be farther away than it actually is, and therefore smaller than the object itself.

It is used to treat a condition called nearsightedness (also called myopia). Also, used in laser, binoculars, telescope, and flashlights.

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Updated on: 10-Oct-2022

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What is a lens? Distinguish between a convex lens and concave lens. Which of the two is a converging lens : convex lens of concave lens?
Concave Lens
You are provided with a concave mirror, a convex mirror, a concave lens and a convex lens. To obtain an enlarged image of an object you can use either$(a)$. concave mirror or convex mirror.$(b)$. concave mirror or convex lens.$(c)$. concave mirror or concave lens.$(d)$. concave lens or convex lens.
You are provided with a convex mirror, a concave mirror, a convex lens and a concave lens. You can get an inverted image from$(a)$. both concave lens and convex lens.$(b)$. both concave mirror and convex mirror.$(c)$. both concave mirror and convex lens.$(d)$. both convex mirror and concave lens.
The magnification produced by a spherical mirror and a spherical lens is + 0.8.(a) The mirror and lens are both convex (b) The mirror and lens are both concave(c) The mirror is concave but the lens is convex (d) The mirror is convex but the lens is concave
The magnification produced by a spherical lens and a spherical mirror is + 2.0.(a) The lens and mirror are both concave (b) The lens and mirror are both convex(c) The lens is convex but the mirror is concave (d) The lens is concave but the mirror is convex
(a) Explain with the help of a diagram, why the concave lens is also called a perging lens.(b) Define the principal focus of a concave lens.
(a) What type of images can a convex lens make?(b) What type of image is always made by a concave lens?
A convex lens is said to have a real focus and a concave lens a Virtual Focus.Why?
A spherical mirror and a spherical lens each have a focal length of, –15 cm. The mirror and the lens are likely to be:(a) both concave.(b) both convex.(c) the mirror is concave but the lens is convex.(d) the mirror is convex but the lens is concave.
A spherical mirror and a thin spherical lens have each a focal length of -15 cm. Themirror and the lens are likely to be(a) both concave.(b) both convex.(c) the mirror is concave and the lens is convex.(d) the mirror is convex, but the lens is concave.
An image formed by a lens is erect. Such an image could be formed by a$(a)$. convex lens provided the image is smaller than object.$(b)$. concave lens provided the image is smaller than object.$(c)$. concave lens provided the image is larger than object.$(d)$. concave lens provided the image is of the same size.
A spherical mirror and a spherical lens each have a focal length of -10 cm. The mirror and the lens are likely to beboth concaveboth convexthe mirror is concave and the lens is convexthe mirror is convex and the lens is concave
To find focal length of concave lens using convex lens
State two differences between a convex and a concave lens.

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