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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
Where is the image when you look at something in a mirror?
What are the important differences between looking at a photograph of your face and looking at yourself in a plane mirror?
Which type of reflection of light leads to the formation of images?
An extended object in the form of an arrow pointing upward has been placed in front of a plane mirror. Draw a labelled ray-diagram to show the formation of its image.
Define the following terms used in the study of reflection of light by drawing a labelled ray-diagram:
(a) Incident ray
(b) Point of incidence
(c) Normal
(d) Reflected ray
(e) Angle of incidence
(f) Angle of reflection
The image of an object formed by a plane mirror is:
(a) virtual
(b) real
(c) diminished
(d) upside-down
If a ray of light goes from a rarer medium to a denser medium, will it bend towards the normal or away from it?
A ray of light travelling in glass emerges into air. State whether it will bend towards the normal or away from the normal.
Name the phenomenon due to which a swimming pool appears less deep than it really 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?
What is meant by the 'angle of incidence' and the 'angle of refraction' for a ray of light?
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?
When a light ray passes from air into glass, what happens to its speed? Draw a diagram to show which way the ray of light bends.
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.
With the help of a labelled diagram, explain why a tank full of water appears less deep than it actually is.
A vertical ray of light strikes the horizontal surface of some water:
What is the angle of incidence?
A ray of light when passes from glass to air, bends towards the normal.
Image is formed by a mirror due to refraction of light.
Define the principal focus of a concave mirror.
Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s−1.
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.
The laws of reflection hold true for ______.
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The incident rays and refracting rays are on opposite sides of the normal.
Write scientific reason.
The coin disappears in a vessel as it is seen from a specific location. But as soon as the water is poured into the vessel to a certain level, the coin appears.
Write scientific reason.
A pencil appears to be broken near the surface of water.
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.
Which object use the reflection of light?
When light passes from one medium to another the ray gets bent. This property of light is called ______.
How does the light travel?
Light bends as it passes from one medium to another. What is this phenomenon called?
A star appears twinkling into the sky because of the reflection of light by the atmosphere.
A water tank appears shallower when it is viewed from the top due to refraction.
How do twinkling stars occur? (or) what is the cause of the twinkling of stars?
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.
