Light Speed in Different Mediums

Light is an electromagnetic wave traveling at 300,000 km/s in a vacuum. When it passes through mediums like air, water, or glass, its speed decreases due to absorption and re-emission by atoms. This process involves temporary vibrations of electrons, delaying light's transmission. In water, light travels at 75% of its vacuum speed, in glass at 67%, and in diamond at 41%.

What is the speed of light in a vacuum?

• 150,000 kilometers per second

• 600,000 kilometers per second

• 300,000 kilometers per second

• 450,000 kilometers per second

What happens to light when it enters a medium like glass?

• It slows down

• It maintains the same speed

• It stops completely

• It speeds up

How do atoms in a material affect the speed of light?

• They completely block the light energy

• They reflect the light energy

• They absorb and re-emit the light energy

• They amplify the light energy

What causes the temporary vibrations in atoms when light is absorbed?

• The rigidity of the atoms

• The elasticity of imaginary springs

• The density of the material

• The elasticity of the nucleus

What is the net effect of absorption and re-emission on light's speed through a medium?

• It decreases the speed

• It stops the light

• It increases the speed

• It has no effect

What is the speed of light in water compared to its speed in a vacuum?

• 50% of its speed in a vacuum

• 75% of its speed in a vacuum

• 90% of its speed in a vacuum

• 100% of its speed in a vacuum

How fast does light travel through glass compared to a vacuum?

• 100% of its speed in a vacuum

• 90% of its speed in a vacuum

• 80% of its speed in a vacuum

• 67% of its speed in a vacuum

What is the speed of light in a diamond compared to a vacuum?

• 70% of its speed in a vacuum

• 41% of its speed in a vacuum

• 50% of its speed in a vacuum

• 60% of its speed in a vacuum

What is the speed of light in glass in kilometers per second?

• 150,000 km/s

• 250,000 km/s

• 200,000 km/s

• 225,000 km/s

Which material slows down light the most?

• Air

• Water

• Diamond

• Glass