| Graphs are one way of showing the relationship between two variables (things that can change in value). |
| The graph above shows how
the brightness of the sun is related to the time of day.
From the start at the bottom left hand corner until just before 6 am brightness is zero. (It is dark). Brightness increases as time passes being at maximum about 1 pm when the sun is highest in the sky. Brightness then falls becoming dark at about 9 pm when the sun sets. Now look at the following graph. |
| This relates a dry battery
voltage to time. It falls slowly over the weeks.
This next graph shows a voltage which slowly rises from zero to a maximum value and then falls suddenly to zero again. |
| This next graph shows the same thing happening but continues repeating. This is called a WAVEFORM. |
| The next waveform is called
a square waveform because of its shape.
It is at zero for a time and then shoots rapidly to a maximum value and stays there for a time before falling to zero again. It then repeats itself continuously. |
| An OSCILLOSCOPE is used
to display and measure waveforms.
A common waveform is the SINEWAVE which can alternate between positive and negative voltages. |
| Note that the horizontal line in all these graphs is called the X axis and the vertical line is the Y axis. |
Copyright Graham Knott 1999