Question

1. If a student measures the speed of light to be 2.4587 × 10⁸ m/s, then do they have a problem with their accuracy, their precision or both given that the accepted value is 2.9979 × 10⁸ m/s?

Answer 1

Before jumping to the conclusion let's first define the terms accuracy and precision.

Accuracy: it is the degree of closeness of a measured quantity with it's true value of the physical quantity is termed as accuracy of the measurement.

For example; true length of a bar is 100mm and one measurement shows 99.9mm and an other measurement shows 99.6mm. In this case first measurement is more accurate than second measurement.

As in our case the measured value of speed of light is much lesser than the actual value. So it has a problem in accuracy. Because the measured value is about 81.9% of the true value.

Precision: it is defined as the measure of the 'extent' to which sucessive measurements of physical quantity differ from one another.

For example: the true value of a measurement is 10.623 and one of the measured value is 10.231 and other measured value is 10.5, here first measured value is less accurate than the second measured value but it's more precise than the second measured value because the measurement is done upto 3 decimal places.

As in our problem the degree of precision of both the datas: measured data(2.4587 x 10^8) and true data(2.9979 x 10^8) are same. So it doesn't have any problem in precision.