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Light enters from air to glass having a refractive index of 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 x 108 m/s.
By BYJU'S Exam Prep
Updated on: September 25th, 2023
If light enters glass from the air with a refractive index 1.50, the speed of light is 2 x 108 m/s while the speed of light in a vacuum is 3 x 108 m/s. Steps to calculate the speed of light in a vacuum:
Step 1: It is given that
Speed of light in any medium = speed of light in a vacuum.
Speed of light in vacuum (c) = 3 x 108 m/s
Therefore, the speed of light in the air (c) is 3 x 108 m/s
Refractive index of glass (ng) = 1.5
Step 2: We can use the formula
Speed of light in a glass (v) = Speed of light in the air (c)/ Refractive index of glass (ng)
Step 3: Substituting the values
We know that,
Speed of light in a glass (v) = Speed of light in the air (c)/ Refractive index of glass (ng)
v = c/ng
v = 3 x 108/ 1.5
v = 2 x 108 m/s
Speed of Light in Vacuum
Units of speed include:
- the SI derived unit; metres per second (symbol m s−1 or m/s),
- knots (nautical miles per hour, symbol kn or kt);
- kilometers per hour (symbol km/h);
- Mach number (dimensionless), speed divided by the speed of sound;
- miles per hour (symbol mi/h or mph);
- in natural units (dimensionless), speed is divided by the speed of light in a vacuum
- feet per second (symbol fps or ft/s);
Therefore, the speed of light in the glass is 2 x 108 m/s
Summary:
Light enters from air to glass having a refractive index of 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 x 108 m/s.
Light enters from air to glass having a refractive index of 1.50. The speed of light in the glass is 2 x 108 m/s. The speed of light in a vacuum is 3 x 108 m/s. The refractive index of a medium is how the light travels via that medium.