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प्रश्न
State the uses of plane mirrors.
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उत्तर
Uses of a plane mirror:
- Plane mirrors are used to see ourselves. Example, mirrors in a bathroom.
- Plane mirrors are fixed on the inner walls of certain shops ( like jewellery shops) to make them look bigger.
- Plane mirrors are fitted at blind turns of some busy roads so that drivers can see the vehicles coming from the other side and prevent accidents.
- Plane mirrors are used in periscopes.
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संबंधित प्रश्न
State whether the following statement is true of false:
A student says that we can see an object because light from our eyes is reflected back by the object.
A boy with a mouth 5 cm wide stands 2 m away from a plane mirror. Where is his image and how wide is the image of his mouth?
The boy walks towards the mirror at a speed of 1 m/s. At what speed does his image approach him?
The speed of light is more in glass than in water.
When a ray of light travels from water to air, it bends ............. the normal.
A ray of light passes from medium 1 to medium 2. Which of the following quantities of the refracted ray will differ from that of the incident ray: Speed, intensity, frequency, wavelength?
The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to `1/3` rd of its size . Find the distance of the object from the optical centre of the lens .
Right or wrong sentence.
The incident rays and refracted rays are on opposite sides of the column.
Numerical problems.
The speed of light in water is 2.25 × 108 ms–1. If the speed of light in vacuum is 3 × 108 ms–1, calculate the refractive index of water.
Noor, a young student, was trying to demonstrate some properties of light in her Science project work. She kept ‘X’ inside the box (as shown in the figure) and with the help of a laser pointer made light rays pass through the holes on one side of the box. She had a small butter-paper screen to see the spots of light being cast as they emerged.
Her friend noted the following observations from this demonstration:
- Glass is optically rarer than air.
- Air and glass allow light to pass through them with the same velocity.
- Air is optically rarer than glass.
- Speed of light through a denser medium is faster than that of a rarer medium.
- The ratio: sin of angle of incidence in the first medium to the ratio of sin of angle of refraction in the second medium, gives the refractive index of the second material with respect to the first one.
Which one of the combinations of the above statements given below is correct.
Light travels fastest in a vacuum. Why?
The ratio of the sine of the angle of incidence to the sine of ______ is constant.
The bottom of swimming pool appears to be less deep than the actual one because of
A ray of light starting from diamond is incident on the interface separating diamond and water. Draw a labelled ray diagram to show. the refraction of light in this case.
When a ray of light travels normal to the given surface, then the angle of refraction is ______.
A normal is an imaginary line drawn ________ to the boundary at the point of incidence.
When light travels from a rarer medium to a denser medium, its speed:
When light travels from a denser medium to a rarer medium, its speed:
To a crane, a fish appears 6 cm below the water surface. Taking the refractive index of water as \[\frac{4}{3}\], the real depth of the fish below the surface is:
