Measurement of Length (Indirect Method)

Description:

Indirect Method

When we cannot reach both the ends of length, the measurement is done by indirect method. The use of indirect method is again classified depending upon the distance −

• Large distance
• Small distance

Large distance

For measurement of length of large distance we use the following indirect methods −

We calculate the length using a formula −

length = velocity × time

In this method, the phenomenon of reflection is used to calculate the length/distance.

Example

If a man wants to know the distance of a wall from his current position, then that man will create a sound signal that will hit the surface of the wall and return back, by measuring the time required for the wave to come back and the velocity of wave, distance can be calculated using the above equation.

This indirect method is also used by ships to measure depth and locate foreign objects in sea. Ships use ultra-sound to implement this method.

Another application of this method which is implemented using ultra-sound is for sonography i.e. medical use.

For the calculation of distance between planets radio waves are used, the process of measurement of distance is done using this indirect method itself.