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.

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.

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 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 convex mirror whose radius of curvature is 32 cm.

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

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

We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.

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?

Why do you think the noble gases are placed in a separate group?

Which of the following is a plant hormone?

(a) Insulin
(b) Thyroxin
(c) Oestrogen
(d) Cytokinin.

The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

        (a) cytoplasm.               (c) chloroplast.
        (b) mitochondria.           (d) nucleus.

The device used for producing electric current is called a

(a) generator.
(b) galvanometer.
(c) ammeter.
(d) motor.

How is the equal genetic contribution of male and female parents ensured in the progeny?

What were the limitations of Döbereiner’s classification?

By considering their position in the Periodic Table, which one of the following elements would you expect to have maximum metallic characteristic?
Ga     Ge      As     Se     Be

Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?

How does the embryo get nourishment inside the mother’s body?

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.