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प्रश्न
What is the speed of light in vacuum?
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उत्तर
The speed of light in vacuum is known to be almost exactly 300,000 km per second. In 1665 the Danish astronomer Ole Roemer first estimated the speed of light by observing one of the twelve moons of the planet Jupiter.
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संबंधित प्रश्न
State the speed of light in (a) air, (b) glass.
State whether light slows down or speeds up in the following cases :
Light going from air to glass.
State whether light slows down or speeds up in the following cases :
Light going from glass to water.
State whether light slows down or speeds up in the following cases :
Light going from water to air.
A light ray passes from water to
- air, and
- glass.
In each case, state how does the speed of light change.
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.
An obliquely incident light ray bends at the surface due to a change in speed when passing from one medium to another. The ray does not bend when it is incident normally. Will the ray have a different speed in the other medium?
Numerical problem.
Light enters from air into a glass plate having refractive index 1.5. What is the speed of light in glass? (Ans: 2 × 108 ms–1)
Objects that allow light to pass through partially are called ______ material.
Two medium with a refractive index of 1.31 & 1.50 is given. In which case
- The bending of light is more and
- speed of light is more.
