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प्रश्न
Lights of different colours are used as signal for safety transport. From these, the wavelength of red light is _______ nm.
पर्याय
400
500
600
700
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उत्तर
Lights of different colours are used as signal for safety transport. From these, the wavelength of red light is 700 nm.
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संबंधित प्रश्न
A wall reflects light and a mirror also reflects light. What difference is three in the way they reflect light?
Which type of reflection of light leads to the formation of images?
The angle of reflection is equal to the angle of incidence:
(a) always
(b) sometimes
(c) under special conditions
(d) never
The figure given alongside shows the image of a clock as seen a plane mirror. The correct time is:
Figure
(a) 2.25
(b) 2.35
(c) 6.45
(d) 9.25
A man stands 10 m in front of a large plane mirror. How far must the walk before he is 5 m away from his image?
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?
With the help of a labelled diagram, explain why a tank full of water appears less deep than it actually is.
Name the phenomenon due to which a pencil partly immersed in water and held obliquely appears to be bent at the water surface.
State two factors on which the lateral displacement of the emergent ray depends.
Light travelling from a denser medium to a rarer medium along a normal to the boundary:
(a) is refracted towards the normal
(b) is refracted away from the normal
(c) goes along the boundary
(d) is not refracted
A vertical ray of light strikes the horizontal surface of some water:
What is the angle of incidence?
A vertical ray of light strikes the horizontal surface of some water:
What is the angle of refraction?
How does the light have to enter the glass:
for no refraction to happen?
A ray of light when passes from glass to air, bends towards the normal.
The speed of light is more in glass than in water.
Water is optically .......... than air.
Air is optically .......... than glass.
What do you understand by refraction of light?
Draw suitable diagrams to illustrate how a beam of light incident parallel to the principal axis is reflected by:
(a) a concave mirror, and (b) a convex mirror
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.
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 .
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.
Explain with diagrams how refraction of incident light takes place from
- rarer to denser medium
- denser to rarer medium
- normal to the surface separating the two media.
The angle of incidence for a ray of light having zero reflection angle is ______.
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 bends as it passes from one medium to another. What is this phenomenon called?
A ray of light traveling in medium 1 strikes and travels into another transparent medium 2. If the speed of light is greater in medium 1, the ray will ______.
Mirage is an example of refraction and the total internal reflection of light.
A water tank appears shallower when it is viewed from the top due to refraction.
Assertion: The air bubble shines in water.
Reason: Air bubble shines due to the refraction of light.
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.
