Two different types of lenses are placed on a sheet of newspaper. How will you identify them without touching?
Answer: The lens is a convex lens if the letters appear magnified and the lens is concave if the image... View Article
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An erect and enlarged image of an object is formed on a screen. Explain how this could be possible.
Answer: An erect and enlarged image of an object is formed on a screen if the object is placed upside... View Article
The concave reflecting surface of a torch got rusted. What effect would this have on the beam of light from the torch?
Answer: If a torch’s concave reflecting surface becomes rusted, it will no longer create a clear beam of light and... View Article
The side mirror of a scooter got broken. The mechanic replaced it with a plane mirror. Mention any inconvenience that the driver of the scooter will face while using it?
Answer: A driver cannot see the traffic spread over the large area behind him if the side mirror of the... View Article
State the correct sequence (1-7) of colours in the spectrum formed by the prisms A and B, shown in Figure
Answer: When white light is passed through a glass prism it splits into its spectrum of colours in order violet,... View Article
Boojho made light from a laser torch to fall on a prism. Will he be able to observe a band of seven colours? Explain with a reason.
Answer: No, he won’t be able to see the seven-colour band since laser light is composed of only one colour.... View Article
Observe the givenfigure carefully. The given figures show the path of light through lenses of two different types, represented by rectangular boxes A and B. What is the nature of lenses A and B?
Answer: (A) Convex lens A convex lens is a lens with an outward curve. The thickness at the centre of... View Article
What type of mirror is used as a side mirror in a scooter? Why is this type of mirror chosen?
Answer: Convex mirrors are used as a side mirror in a scooter because in Convex mirrors image formed is spread... View Article
State whether the following statements are True or False. (a) A concave lens can be used to produce an enlarged and erect image. (b) A convex lens always produces a real image. (c) The sides of an object and its image formed by a concave mirror are always interchanged. (d) An object can be seen only if it emits light.
Answer: (a) False – A concave lens can be used to produce a diminished and erect image. (b) False –... View Article
The inner surface of a steel spoon acts as a ___________ mirror. (b) The outer surface of a flat steel plate acts as a ___________ mirror. (c) The outer shining surface of a round bottom steel bowl acts as a __________ mirror. (d) The inner surface of the reflector of a torch acts as a __________ mirror.
Answer: (a) The inner surface of a steel spoon acts as a concave mirror. (b) The outer surface of a... View Article
The image formed by a lens is always virtual, erect and smaller in size for an object kept at different positions in front of it. Identify the nature of the lens.
Answer: The Concave lens is also known as a diverging lens. It always forms virtual, erect and smaller images, and... View Article
An image formed by a lens is erect. Such an image could be formed by a (a) convex lens provided the image is smaller than the object. (b) concave lens provided the image is smaller than the object. (c) concave lens provided the image is larger than the object. (d) concave lens provided the image is of the same size.
Answer: (b) concave lens provided the image is smaller than the object. A virtual, erect and diminished image of an... View Article
You are provided with a convex mirror, a concave mirror, a convex lens and a concave lens. You can get an inverted image from (a) both the concave lens and convex lens. (b) both concave mirror and convex mirror. (c) both concave mirror and convex lens. (d) both convex mirror and concave lens.
Answer: (c) both concave mirror and convex lens. A concave mirror and convex lens can only form a real and... View Article
A rainbow can be seen in the sky (a) when the sun is in front of you. (b) when the sun is behind you. (c) when the sun is overhead. (d) only at the time of sunrise.
Answer: (b) when the sun is behind you. Rainbows can only be seen in the sky when the sun is... View Article
You are provided with a concave mirror, a convex mirror, a concave lens and a convex lens. To obtain an enlarged image of an object you can use either (a) concave mirror or convex mirror. (b) concave mirror or convex lens. (c) concave mirror or concave lens. (d) concave lens or convex lens.
Answer: (b) concave mirror or convex lens. Concave mirror and convex lens form enlarged images whereas convex mirror and concave... View Article
If an object is placed at a distance of 0.5 m in front of a plane mirror, the distance between the object and the image formed by the mirror will be (a) 2 m (b) 1 m (c) 0.5 m (d) 0.25 m
Answer: (b) 1 m The image formed by a plane mirror is always virtual and erect. The images formed from... View Article
Which of the following can be used to form a real image? (a) Concave mirror only. (b) Plane mirror only. (c) Convex mirror only. (d) Both concave and convex mirrors
Answer: (a) concave mirror only A concave mirror alone can produce a real image. The plane mirror and convex mirror... View Article
Boojho and Paheli were given one mirror each by their teacher. Boojho found his image to be erect and of the same size whereas Paheli found her image erect and smaller in size. This means that the mirrors of Boojho and Paheli are, respectively (a) plane mirror and concave mirror. (b) concave mirror and convex mirror. (c) plane mirror and convex mirror. (d) convex mirror and plane mirror.
Answer: (c) plane mirror and convex mirror. The plane mirror always forms an image of the same size and erected... View Article
What is biomass? Explain the principle and working of a biogas plant using a labelled schematic diagram.
Answer: Sources of fuel obtained from organic material are called biomass. Cow-dung, various plant materials like the residue after harvesting... View Article
Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answer.
Answer: Energy from various sources is considered to have been derived from the sun. The following points can justify the... View Article
