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प्रश्न
What is the speed of light in vacuum?
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.
A light ray passes from water to
- air, and
- glass.
In each case, state how does the speed of light change.
The speed of light in air is 3 × 108 m s-1. Calculate the speed of light in glass. The refractive index of glass is 1.5.
Compare the speeds of light of wavelength 4000 Å (i.e. violet light) and 8000 Å (i.e. red light) in vacuum.
Materials that allow light to pass through completely are known as ______ material.
Materials that are not able to allow light to pass through, are called ______ material.
Define transparent materials. Give example.
Define opaque material. Give example.
The speed of light decreases in a denser medium, light bends towards the normal.
Light is one of the slowest traveling energy with a speed of 3 × 10-8ms-1
