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Question
Write scientific reason.
A pencil appears to be broken near the surface of water.
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Solution
- When one look at the portion of the pencil that is inside the water, light travels from water to air via glass.
- This light ray changes the medium and undergoes refraction.
- As a result, the pencil inside the water appears to be broken near the surface of water.
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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 ray of light strikes a plane mirror such that its angle of incidence is 30°. What angle does the reflected ray make with the mirror surface?
What is lateral inversion? Explain by giving a suitable example.
What are the important differences between looking at a photograph of your face and looking at yourself in a plane mirror?
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?
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?
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.
State the uses of plane mirrors.
Explain why, though both a plane mirror and a sheet of paper reflect light but we can see the image of our face in a plane mirror but not in a sheet of paper.
An object is placed 20 cm in front of a plane mirror. The mirror is moved 2 cm towards the object. The distance between the positions of the positions of the original and final images seen in the mirror is ______.
State whether the following statement is true or false:
Refraction occurs because light slows down in denser materials.
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 ............
What is meant by 'refraction of light'? Draw a labelled ray diagram to show the refraction of light.
A ray of light travelling in air is incident on a rectangular glass block and emerges out into the air from the opposite face. Draw a labelled ray diagram to show the completer path of this ray of light. Mark the two points where the refraction of light takes place. What can you say about the final direction of ray of light?
Light travels more quickly through water than through glass.
Which is optically denser : water or glass?
With the help of a diagram, show how when light falls obliquely on the side of a rectangular glass slab, the emergent ray is parallel to the incident ray.
A ray of light passes from a medium X to another medium Y. No refraction of light occurs if the ray of light hits the boundary of medium Y at an angle of:
(a) 0°
(b) 45°
(c) 90°
(d) 120°
Image is formed by a mirror due to refraction of light.
Air is optically .......... than glass.
When a ray of light travels from air to glass, it bends .......... the normal.
The diagram (figure) given below shows two parallel rays 1 and 2 incident on (a) a concave mirror, (b) a convex mirror. Draw the reflected rays and mark the focus by the symbol F.
The phenomenon of change in the direction of light when it passes from one transparent medium to another is called ___________.
The laws of reflection hold true for ______.
Identify the wrong figure from the following.
The incident rays and refracting rays are on opposite sides of the normal.
Observe the given figure and write appropriate phenomenon of light in the box.
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.
The deviation of light ray from its path when it travels from one transparent medium to another transparent medium is called ______.
Which surface will not reflect most of the light falling on them?
How does the light travel?
Assertion: The air bubble shines in water.
Reason: Air bubble shines due to the refraction of light.
Under what circumstances there won’t be any refraction of light when it enters from one medium to another?
