A solar water heater cannot be used to get hot water on

Which of the following is not an example of a bio-mass energy source?

A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is.

Under which of the following conditions a concave mirror can form an image larger than the actual object?

The path of a ray of light coming from air passing through a rectangular glass slab traced by four students are shown as A, B, C and D in Figure. Which one of them is correct?

Which one of the following is a renewable resource?
Natural gas, Petrroleum, Ground water, Coal

What is meant by power of a lens?

A ray of light is incident on a concave mirror along its principal axis. What will be the angle of reflection?

Name the lens which always gives an erect and diminished image?

A ray of light is incident on a convex mirror as shown. Redraw the diagram and complete the path of this ray after reflection from the mirror. Mark angle of incidence and angle of reflection on it.

What is a good source of energy?

Compare and contrast fossil fuels and the Sun as direct sources of energy.

What are the limitations of extracting the following energy?
(a) The wind
(b) The waves
(c) The tides

List any four characteristics of biogas on account of which it is considered an ideal fuel

A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Where is the image located?

(a) What is a 'solar cell'?
(b) Why is biogas considered an ideal fuel for domestic use?
(c) Name a device in which controlled chain reaction is used.

(a) Why is the Solar Cooker box covered with a plane glass plate?
(b) Why is energy of water flowering in a river considered to be an indirect form of solar energy?
(c) How is the fission of nucleus brought about?

(a) State one limitation of solar energy available from solar cells.
(b) What is the minimum wind velocity required to obtain useful energy with a windmill?
(c) Define the term 'nuclear fission'.

a) Why is there a need for harnessing non-conventional sources of energy?
b) How can energy be harnessed from the sea in different ways?

Energy from various sources is considered to have been derived from the sun. do you agree? Justify your answer.

(i) Write the value of solar constant of Sun.
(ii) What type of mirror is used in Box Type Solar Cooker?
(iii) Why it is difficult to use hydrogen as a source of energy?
(iv) Fossil fuels are classified as non-renewable source of energy. Explain why.

(i) Distinguish between renewable and non-renewable sources of energy giving one example of each.
(ii) Why is the use of wood as a fuel not advised although forests can be replenished?

(a) Define focal length of a divergent lens.
(b) A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object from the lens and the size of the image formed.
(c) Draw a ray diagram to show the formation of image in the above situation.