Advertisements
Advertisements
Question
Which of the following lens would you prefer to use while reading small letters found in a dictionary?
Options
A convex lens of focal length 5 cm
A concave lens of focal length 5 cm
A convex lens of focal length 10 cm
A concave lens of focal length 10 cm
Advertisements
Solution
A convex lens of focal length 5 cm
APPEARS IN
RELATED QUESTIONS
A lens forms an upright and diminished image of an object when the object is placed at its focal point. Name the lens and draw a ray diagram to show the image formation.
Draw a ray diagram to show how a converging lens can form a real and enlarged image of an object.
Draw a ray diagram to show how a converging lens can form an image of the sun. Hence give a reason for the term ‘burning glass’ for a converging lens used in this manner.
Where should an object be placed so that a real and inverted image of the same size is obtained by a convex lens?
A small bulb is placed at the principal focus of a convex lens. When the bulb is switched on, the lens will produce
An object is placed at a distance 20cm from a convex lens of focal length 10cm. Find the image distance and nature of the image.
Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15 cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? What is the approximate focal length of this lens?
Draw ray diagrams showing the image formation by a convex lens when an object is placed
- between optical centre and focus of the lens
- between focus and twice the focal length of the lens
- at twice the focal length of the lens
- at infinity
- at the focus of the lens
Complete the following table based on image formation by convex lens:
| Position of Object | Position of Image | Nature of Image |
| At infinity | (a) ______ | Real and inverted and highly diminished image |
| Beyond 2F1 | (b) ______ | (c) ______ |
| At 2F1 | (d) ______ | Real, inverted, same size (as object) image |
| Between F1 and 2F1 | Beyond 2F2 | (e) ______ |
| At focus F1 | (f) ______ | Real, inverted and highly enlarged image |
A lens forms an upright and magnified image of an object. Draw a labelled ray diagram to show the image formation.
