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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 down between F(focus) and 2F(centre of... 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 instead will emit light with... 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 scooter is replaced with a plane mirror.... 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, indigo, blue, green, yellow,... 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. If white light was made to fall on a... 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 is a lens with an outward curve. The thickness at the centre of a convex lens is more than the thickness at the edges... 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 over a large area. This will help... 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 - A convex lens always produces a virtual... 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 flat steel plate acts as a plane mirror. (c)... 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 the image is formed in front... 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 object is formed by a concave... 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 inverted image of an object. A convex... 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 behind us since the rainbow reflects the sun's... 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 lens form... 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 plane mirrors are the reflected images in... 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 form a virtual image of an... 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 image. Convex mirror forms... 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 statement. Energy from... View Article

What are the environmental consequences of using fossil fuels? Suggest the steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy.

Answer: The substances which act as energy sources are known as fuels. The buried organic matters which can be converted to crude oil, coal,... View Article

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