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प्रश्न
Write scientific reason.
The sun appears on the western horizon for some time after sunset.
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उत्तर
- As ray of light from the Sun enters the earth’s atmosphere, it follows a curved path due to refraction, before reaching the observer.
- This makes the apparent position of the Sun slightly higher than the actual position for the observer.
- Hence, due to the atmospheric refraction of sunlight, the observer on the earth continues to see the setting Sun for two minutes after the Sun has dipped below the horizon, thus delaying the sunset.
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संबंधित प्रश्न
What is refraction of light?
The letter F is placed in front of a plane mirror:
- How would its image look like when seen in a plane mirror?
- What is the name of the phenomenon involved?
The boy walks towards the mirror at a speed of 1 m/s. At what speed does his image approach him?
The angle of reflection is equal to the angle of incidence:
(a) always
(b) sometimes
(c) under special conditions
(d) never
A ray of light strikes a plane mirror PQ at an angle of incidence of 30°, is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is ______.
A ray of light passes from air into a block of glass. Does it bend towards the normal or away from it?
Why does a ray of light bend when it travels from one medium to another?
Fill in the following blank with suitable word:
Light bends when is passes from water into air. We say that it is ............
Light travels more quickly through water than through glass.
If a ray of light passes from glass into water, which way will it bend : towards the normal or away from the normal?
A coin in a glass tumbler appears to rise as the glass tumbler is slowly filled with water. Name the phenomenon responsible for this effect.
Name the phenomenon due to which a pencil partly immersed in water and held obliquely appears to be bent at the water surface.
A vertical ray of light strikes the horizontal surface of some water:
- What is the angle of incidence?
- What is the angle of refraction?
How does the light have to enter the glass:
to produce a large amount of bending?
The depth of a pond when seen from above appears to be less.
Light travels at a lower speed in water than in air.
When a ray of light travels from air to glass, it bends .......... the normal.
What do you understand by refraction of light?
A light ray suffers reflection and refraction at the boundary in passing from air to water. Draw a neat labelled ray diagram to show it.
A ray of light A incident from air suffers partial reflection and refraction at the boundary of water.
- Complete the diagram showing (i) the reflected ray B and (ii) the refracted ray C.
- How are the angles of incidence i and refraction r related?
A small air bubble in a glass block when seen from above appears to be raised because of ______.
We can see the sun even when it is little below the horizon because of ______.
Define the principal focus of a concave mirror.
List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre.
List in proper sequence the steps of the experiment for determining the approximate focal length of a given concave mirror by obtaining the image of a distant object.
The phenomenon of change in the direction of light when it passes from one transparent medium to another is called ___________.
The incident rays and refracting rays are on opposite sides of the normal.
Write scientific reason.
The bottom of a pond appears raised.
Assertion and reasoning type
- Assertion: If the refractive index of the medium is high (denser medium) the velocity of the light in that medium will be small
- Reason: Refractive index of the medium is inversely proportional to the velocity of the light
What is refractive index?
The angle of incidence from air to glass at the point O on the hemispherical glass slab is.
When light passes from one medium to another the ray gets bent. This property of light is called ______.
Light travels fastest in a vacuum. Why?
The bending of light as it passes from one medium to another is called ______.
Mirage is an example of refraction and the total internal reflection of light.
Assertion: The air bubble shines in water.
Reason: Air bubble shines due to the refraction of light.
Which is optically denser out of the two medium M1& M2 having the refractive indices = 1.71 and 1.36 respectively?
Under what circumstances there won’t be any refraction of light when it enters from one medium to another?
In refraction of light through a glass slab, the directions of the incident ray and the refracted ray are ______.
