A small electric lamp is placed at the focus of a convex lens. State the nature of beam of light produced by the lens. Draw a diagram to show this.
When an object is placed at the focus of a converging lens then the light rays from the object will get refracted from the convex lens and become parallel to the principal axis. The image will be formed at infinity.
So, if a small electric lamp is placed at the focus of a convex lens, a beam of light is produced which is parallel to the principal axis.
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- A ray of light is going towards the focus of a concave lens. draw a ray diagram to show the path of this ray of light after refraction through the lens.
- A small bulb is placed at the focal point of a converging lens. When the bulb is switched on, the lens produces:(a) a convergent beam of light (b) a pergent beam of light(c) a parallel beam of light (d) a patch of coloured light
- (a) With the help of a labelled diagram explain how a convex lens converges a beam of parallel light rays. Mark the principal axis, optical centre, principal focus and focal length of the convex lens on the diagram.(b) State whether convex lens has a real focus or a virtual focus.(c) List some things that convex lens and concave mirror have in common.
- What is the nature of the image formed by a convex lens if the magnification produced by the lens is +3?
- What is the nature of the image formed by a convex lens if the magnification produced by the lens is, $-$ 0.5?
- (a) Draw a diagram to show how a converging lens focusses parallel rays of light?(b) How would you alter the above diagram to show how a converging lens can produce a beam of parallel rays of light.
- If an object is placed at the focus of a convex lens, where is the image formed?
- An object is placed at a distance equal to 2f in front of a convex lens. Draw a labelled ray diagram to show the formation of image. State two characteristics of the image formed.
- (a) Explain with the help of a diagram, why the convex lens is also called a converging lens.(b) Define principal axis, principal focus and focal length of a convex lens.
- Describe with the help of a ray-diagram, the size, nature and position of the image formed by a convex lens when an object is placed beyond 2f in front of the lens.
- Draw a ray diagram to show the formation of a real magnified image by a convex lens. (In your sketch the position of object and image with respect to the principal focus of lens should be shown clearly).
- (a) What is meant by (i) principal focus of a convex mirror, and (ii) focal length of a convex mirror?(b) Draw diagram to show the action of convex mirror on a beam of parallel light rays. Mark on this diagram principal axis, focus F, centre of curvature C, pole P and focal length f, of the convex mirror.
- 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?
- Things always look small on viewing through a lens. What is the nature of the lens?
- (a) With the help of a labelled diagram, explain how a concave lens perges a beam of parallel light rays. Mark the principal axis, optical centre, principal focus and focal length of the concave lens on the diagram.(b) State whether concave lens has a real focus or a virtual focus.(c) List some things that concave lens and concave mirror have in common.
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