[accordion title="1. Base and Derived Quantities"]
- Physical quantities are classified as base (or fundamental) quantities and derived quantities.
7 base quantities are chosen to form the base units.
|Base Quantity||Base Unit|
|electric current||ampere (A)|
|amount of substance||mole (mol)|
|luminous intensity||candela (cd)|
- Any other physical quantities can be derived from these base quantities. These are called derived quantities.
[accordion title="2. Prefixes"]
- Prefixes are attached to a unit when dealing with very large or very small numbers.
[accordion title="3. Homogeneity of A Physical Equation"]
- A physical equation is said to be homogeneous if each of the terms, separated by plus, minus, equality or inequality signs has the same base units.
[accordion title="4. Uncertainty"]
- Absolute uncertainty of a measurement of can be written as . This means that true value of the measurement is likely to lie in the range to .
- Fractional uncertainty =
- Percentage uncertainty =
- If the values of two or more quantities such as and are measured and then these are combined to determine another quantity , the absolute or percentage uncertainty of can be calculated as follows:
- If , then
- If or , then
- If then
[accordion title="5. Errors"]
- Systematic errors are errors that, upon repeating the measurement under the same conditions, yield readings with error of same magnitude and sign.
- Random errors are errors that, upon repeating the measurement under the same conditions, yield readings with error of different magnitude and sign.
[accordion title="6. Accuracy and Precision"]
- The accuracy of an experiment is a measure of how close a measured value is to the true value. It is a measure of the correctness of the result.
- The precision of an experiment is a measure of how exact the result is without reference to what that the result means. It is a measure of how reproducible the results are, i.e. it is a measure of how small the uncertainty is.
[accordion title="7. Vectors"]
- A vector quantity has magnitude and direction.
- A scalar quantity has magnitude only.
- Addition of vectors in 2D:
- Methods of finding magnitudes of vectors:
- resolution of vectors into perpendicular components
- by scale drawing