Measurement and Standard Units Quiz

Questions and Answers

Measuring weight with a balance

Establishing empirical relations

To compare the unknown quantity with a known quantity

By measuring the temperature of the fluid Signup and view all the answers

Null methods eliminate the action of unknown quantity by a known counter quantity Signup and view all the answers

They establish an empirical relation with easily measurable related parameters Signup and view all the answers

To express the value of an unknown quantity in terms of a standard unit Signup and view all the answers

Both A and B Signup and view all the answers

A device used to compare an unknown quantity with a standard unit Signup and view all the answers

By directly measuring the unknown quantity itself Signup and view all the answers

To directly indicate the value of the unknown quantity Signup and view all the answers

Null methods and differential methods Signup and view all the answers

Study Notes

Measurement is a quantitative comparison between a given quantity and a standard unit of the same kind.
The result of measurement is expressed by a pointer deflection over a predefined scale or a number representing the ratio between the unknown quantity and the standard.
A standard is defined as the physical personification of the unit of measurement or its submultiple or multiple values.

Direct measurement methods involve measuring the unknown quantity directly without comparing it with a standard.
Examples include measurement of weight by a balance, measurement of resistance, capacitance, and inductance by bridge circuits.

Comparison methods involve direct comparison of the unknown quantity with a standard of the same kind.
Examples include measurement of e.m.f by comparison with the e.m.f of a standard cell.

In the null method, the action of the unknown quantity upon the instrument is reduced to zero by the counter action of a known quantity of the same kind.

In the differential method, the quantity to be measured is compared with a known quantity and the difference between these two is made zero.

Indirect measurement methods involve comparing the unknown quantity with a standard using a calibrated system.
These methods are used when the desired parameter to be measured is difficult to measure directly, but has a relation with another parameter that can be easily measured.
Example: measuring bacteria elimination by measuring the temperature of the fluid, as the elimination is directly dependent upon the temperature.