## A student studies that speed of light in air is 300000 kms

A student studies that speed of light in air is 300000 kms/ sec where that of speed in aglass slab is about 197000 kms/ sec. What causes the difference in speed of light in these two media?​

density of the medium…….

Important Points:

Speed: Speed is defined as the rate of change of position of an object in any direction.

The mathematical representation of speed is:

Speed=Distance / Time

## Types of Speed

There are four types of speed and they are:

• Uniform speed
• Variable speed
• Average speed
• Instantaneous speed

Uniform speed: A object is said to be in uniform speed when the object covers equal distance in equal time intervals.

Variable speed: A object is said to be in variable speed when the object covers a different distance at equal intervals of times.

Average speed: Average speed is defined as the uniform speed which is given by the ratio of total distance travelled by an object to the total time taken by the object.

Instantaneous speed: When an object is moving with variable speed, then the speed of that object at any instant of time is known as instantaneous speed.