# Period

## Key Stage 3

### Meaning

A period is the time taken for one complete wave to pass a point.

A period is measured in seconds.

## Key Stage 4

### Meaning

A period is the time taken for a single oscillation to occur.

A period is a scalar quantity because it has magnitude but no direction.
The SI Unit of a period is seconds.
Period may refer to the time taken for an oscillating object such as a pendulum or mass on a spring to make one full oscillation.
Period may refer to the time taken for one wave to pass a point.

### Equation

NB: You do not need to remember this equation but you should be able to find the period of a wave using the frequency.

Period = 1/(Frequency)

$$T = \frac{1}{f}$$

Where:

f = Frequency

T = time period (the time it takes for one wave to pass a point).

### Example Calculations

 A wave has a frequency of 0.2Hz. Calculate how long it takes for one wave to pass a point. The E-string on a bass guitar is plucked to produce a sound with a frequency of 41.25Hz. Calculate the time it takes for the E-string to make one full oscillation. 1. State the known quantities f = 0.2Hz 1. State the known quantities f = 41.25Hz 2. Substitute the numbers into the equation and solve. $$T = \frac{1}{0.2}$$ $$T = 5s$$ 2. Substitute the numbers into the equation and solve. $$T = \frac{1}{40}$$ $$T = 0.024s$$

### References

#### AQA

Period (waves), page 190, GCSE Combined Science Trilogy; Physics, CGP, AQA
Period (waves), page 227, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Period (waves), pages 219, 220, GCSE Combined Science; The Revision Guide, CGP, AQA
Period of a wave (T), page 183, GCSE Physics, Hodder, AQA
Period of wave, pages 257, GCSE Combined Science Trilogy 2, Hodder, AQA
Period, page 73, GCSE Physics; The Revision Guide, CGP, AQA

#### Edexcel

Period (of a wave), page 49, GCSE Physics, Pearson Edexcel
Period (wave), page 32, GCSE Physics; The Revision Guide, CGP, Edexcel
Period (waves), page 91, GCSE Physics, CGP, Edexcel
Periods (waves), page 164, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Periods, page 18, GCSE Chemistry; The Revision Guide, CGP, Edexcel

#### OCR

Period (of a wave), page 59, Gateway GCSE Physics; The Revision Guide, CGP, OCR
Period (waves), pages 142-143, Gateway GCSE Physics, Oxford, OCR
Periods (in the periodic table), page 87, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Periods (of a wave), page 186, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Periods, page 16, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR