Class 10 Science - Chapter Light - Reflection and Refraction NCERT Solutions | Find out, from Table 10.3, the medium ha

One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.

An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position of the image, its nature and size.

An object 5 cm in length is held 25 cm away from a converging lens of focal length 10 cm. Draw the ray diagram and find the position, size and the nature of the image formed.

A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.

You are given kerosene, turpentine and water. In which of these does the light travel fastest? Use the information given in Table 10.3.

Define 1 dioptre of power of a lens.

Find the focal length of a lens of power – 2.0 D. What type of lens is this?

Find the focal length of a convex mirror whose radius of curvature is 32 cm.

The magnification produced by a plane mirror is +1. What does this mean?

Name the type of mirror used in the following situations.

(a) Headlights of a car.
(b) Side/rear-view mirror of a vehicle.
(c) Solar furnace.

Support your answer with reason.

Did Döbereiner’s triads also exist in the columns of Newlands’ Octaves? Compare and find out.

What is a good source of energy?

Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?

What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

What changes can you make in your habits to become more environment-friendly?

What is the difference between a reflex action and walking?

What is the importance of DNA copying in reproduction?

If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Why should a magnesium ribbon be cleared before burning in air?

You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

Compounds such as alcohols and glucose also contain hydrogen but are not categorised as acids. Describe an Activity to prove it.

Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?

How does reproduction help in providing stability to populations of species?

Define the following terms.

   (i) Mineral          (ii) Ore          (iii) Gangue

In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Which part of the brain maintains posture and equilibrium of the body?

What are the problems caused by the non-biodegradable wastes that we generate?

The gap between two neurons is called a

(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.

How is the small intestine designed to absorb digested food?

Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?