Question

A camera is an optical instrument which makes use of a
A) Convex lens
B) Concave lens
C) Cylindrical lens
D) None of these

Answer 1

A camera is an optical instrument which captures photos by focusing the light rays coming from a distant object onto a film or screen. Hence, it must use a lens that can do this task properly, that is, a lens that can converge the light rays coming from a distant object onto a screen or film.

Complete answer:
A camera is an optical instrument that is used to click and capture photos of objects. The main working idea of a camera is that it gathers the light rays coming from a distant object and then focuses them on a screen or film that is situated inside the camera, thus producing an image of the object.
Hence, to do this, the camera should use a lens that is able to converge the light rays from a distant object and focus them at a point.
Therefore, the camera uses a convex lens. The convex lens converges the light rays coming from a distant object and focuses them on the screen (film) that is present inside the camera and hence, produces an image of the object.

Therefore, the correct option is A) Convex lens.

Note:
Students must note that a concave lens cannot do the task required in the camera because it diverges the light rays form an object and hence produces a virtual image that is not obtained upon the screen or film inside the camera. Therefore, essentially no image is captured.
Our eye lens is also a convex lens that works on the same principle of focusing light rays from different objects onto a screen (the retina). Hence, it often said that our eye is similar to a camera and is termed as the ‘human camera’.