State the laws of reflection. Answer: The angle of incidence is equal to the angle of reflection. i.e. ∠i = ∠r The incident ray, the reflected ray…
Angle of incidence is equal to the angle of reflection (a) Always (b) Sometimes (c) Under special conditions (d) Never Answer: (a) Always. Accordin…
Image formed by a plane mirror is (a) virtual, behind the mirror and enlarged (b) virtual, behind the mirror and of the same size as the object (c) r…
Describe the construction of a kaleidoscope. Answer: The kaleidoscope is a simple toy that uses the idea of multiple images formed by the combinat…
Draw a labeled sketch of the human eye. Answer: (Ref Fig 16.14 in the book) But , A Guide Is Here The human eye is an organ that reacts to light an…
Gurmit wanted to perform Activity 16.8 using a laser torch. Her teacher advised her not to do so. Can you explain the basis of the teacher advise? An…
Explain how you can take care of your eyes. Answer: We should take the following precautionary measures for our eyes: 1. We should wash our eyes tw…
What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray? Answer: According to the laws of reflection,…
How many images of a candle will be formed if it is placed between two parallel plane mirrors separated by 40 cm? Answer: Infinite number of images …
Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30° as shown in Fig. 16.19. Draw the reflected ray from the second…
Boojho stands at A just on the side of a plane mirror as shown in Fig. 16.20. Can he see himself in the mirror? Also can he see the image of objects …
(a) Find out the position of the image of an object situated at A in the plane mirror. (b) Can Paheli at B see this image? (c) Can Boojho at C see th…
What is a constellation And Name any two constellations. Answer: A group of stars that form a recognizable pattern is called a constellation. Some …
Do all the stars in the sky move And Explain. Answer: Stars are at a distance of millions of km from the earth. Thus, these large distances are expr…
Boojho made the following sketch (Fig. 17.29) of the solar system. Is the sketch correct And If not, correct it. Answer: Correct the sequence of plan…
What is the problem with the periodisation of Indian history that James Mill offers? Answer: James Mill divided the period of Indian History on com…
Why did the British preserve official documents? Answer: They preserved the documents to maintain a permanent record of the official documents. The…
How will the information historians get from old newspapers be different from that found in police reports? Answer: The Police reports were not very…
Why do we try and divide history into different periods? Answer: 1. It is an attempt to capture the characteristics of a time, its central features…
What do you mean by the term 'colonisation'? Answer: The subjugation of one country by another leads to these kinds of political, economic, …