What is Representative Fraction ? Give its advantages and disadvantages.
Representative Fraction is also known as Numerical Function. In this case, the ratio existing between the length on the map and actual length on the ground is indicated by a fraction whose numerator is always 1. This fraction is usually abbreviated as R. F. Thus, Representative Fraction (R.F.)
The most important point to be noted in this connection is that the unit of measurement of distances in numerator and denominator is the same. For example, if we say the R.F. of a map is 1/1,00,000 or 1: 1,00,000, it means that one unit on the map represents 1,00,000 units on the ground. If the unit of measurement is centimetre, we will say that 1 centimetre on the map represents 1,00,000 centimetres on the ground. If, however, the unit of measurement is an inch, then we will say that 1 inch on the map represents 1,00,000 inches on the ground.
Advantages: Since it is only a fraction and is indented of any particular unit of a measurement, it can be used in all the countries. If the R.F. of a map is 1: 1,00,000 to a Britisher, it would mean that 1" on the map represents 1,00,000 inches on the ground. Similarly, to a Frenchman, it would mean that 1 cm on the map represents 1,00,000 inches on the ground and to a Russian, 1 verst on the map represents 1,00,000 versts on the ground. It is also termed as International Scale or Natural Scale. It has become a very popular method of expressing the scale.
Disadvantages :
- It is only a fraction in which no system of units is used. Hence, distances cannot be directly measured from it.
- Whenever a map is photographically enlarged or reduced, the R.F. will no longer be true.
- This is not easily understood by a common man.