# Concept of Time - Simple Pendulum.

Physics

## definition

### Method of measurement of Time

Time is measured using a mechanical, electric or atomic clock. The cesium atomic clocks are the most accurate. Atomic clocks use the frequency of electronic transitions in certain atoms to measure the second. The unit of time is second in SI units. It is defined as cycles of the radiation that corresponds to the transition between two electron spin energy levels of the ground state of the atom.

## definition

### Other common units of time

Smaller units of time: (1) Millisecond (2) Microsecond (3) Shake (4) Nanosecond
Bigger Units of Time: (1) Minute (2) Hour (3) Day (4) Month (5) Lunar Month (6) Year (7) Leap Year (8) Decade (9) Century (10) Millenium

## example

### Some Other Common Units of Time

Some other common units of time include :
1. Second (s)
2. Millisecond (ms)
3. Minute (min)
4. Hour (h)
5. Day (d)

## definition

### Working of a simple pendulum

A simple pendulum has a heavy point mass (known as bob) suspended from a rigid support by a massless and inextensible string. When the bob from its mean position is pulled to one side and then released, the pendulum is set to motion and the bob moves alternately on either side of its mean position.

## definition

### Instruments to measure time

Clock is basic time measuring device, it works on the principle of periodic motion.Clock are of different types table clock, digital clock, wall clock etc.
Simple Pendulum is the basic instrument to measure time period.