Human Eye and Colourful World — Science STD 10 — Question

An extended object in the form of an arrow pointing upward has been placed in front of plane mirror. Draw a labelled ray-diagram to show the formation of its image.

Ciliary muscles of human eye can contract or relax. How does it help in the normal functioning
of the eye?

A fuse wire consists of an alloy of lead and tin. Why?

A convex lens is immersed in a liquid of refractive index greater than that of glass. How will the nature of lens change?

Name some sources of direct current and some of alternating current.

State two advantages of geothermal energy.

An object is placed at the following distance from a convex lens of focal length 15cm:

1. 35cm
2. 30cm
3. 20cm
4. 10cm

Which position of the object will produce:

1. A magnified real image?
2. A magnified virtual image?
3. A diminished real image?
4. An image of same size as the object?

Name any two factors on which the strength of magnetic field produced by a current-carrying solenoid depends. How does it depend on these factors?

How does the thickness of the eye lens change when we shift looking from a distant tree to reading a book?

Name the atmospheric phenomenon due to which the sun can be seen above the horizon about two minutes before actual sunrise.