Class 10 Science - Chapter Light - Reflection and Refraction NCERT Solutions | You are given kerosene, turpentine and w

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.

Find out, from Table 10.3, the medium having highest optical density. Also find the medium with lowest optical density.

     Table 10.3 Absolute refractive index of some material media

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.

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?

Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)

  (a) mass                  (b) speed
  (c) velocity               (d) momentum

How much energy is given to each coulomb of charge passing through a 6 V battery?

Why do stars twinkle?

Which signals will get disrupted in case of a spinal cord injury?

Plaster of Paris should be stored in a moisture-proof container. Explain why?

Translate the following statements into chemical equations and then balance them.

(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.

Why is the use of iodised salt advisable?

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?