To know how to calculate amplitude, you should know what is meant by amplitude. Amplitude is defined as the magnitude of change in oscillation that is variable with each oscillation within an oscillating system. In case of sound waves in air amplitude is proportional to the change in pressure. In a wave the amplitude is the extreme point of the wave from the baseline which is the line passing exactly through the middle of the wave.
The method of calculation of amplitude depends upon the available data with you. You may choose to determine amplitude experimentally or if you want to do it manually then you need to use some trigonometric equations.
Calculating amplitude
The general equation, Y=baseline + Amplitude + sin (frequency X + offset) tells you the exact location of the amplitude.
Steps to calculate amplitude
Step 1: Draw x and y co-ordinates on a paper. Draw a table containing x and y values.
Insert the values in the equation y=sin(x + π/2), y = sin(x +3π/2), etc.
Suppose we insert the values for x as 1 and 2 in the equation y=sin(x + π/2)
When, x=1
Y = sin (1 + π/2)
Y = sin (1 + 3.14/2)
Y =0.54
When, x=2
Y = sin (2 + π/2)
Y = sin (2 + 3.14/2)
Y = -0.42
Follow this procedure until the values in for y start repeating. When the values start repeating, you will get a complete revolution of the wave.
Step 2: Place all the values in the table and locate the highest number in the table. This value is the amplitude of your wave.
Step 3: You can also plot the points on the x and y co-ordinates drawn. Draw a wave joining these points. The farthest point of the wave is your amplitude.
Calculating amplitude using a CRO
When you want to calculate amplitude of a circuit then we use CRO (Cathode Ray Oscilloscope). You can measure the voltage amplitude as well as current amplitude using a CRO. A CRO consists of horizontal and vertical grids.
Step 1: Connect the wires of your circuit to the CRO using the crocodile pins. Connect the circuit in parallel to the CRO.
Step 2: Look for the sinusoidal wave on the oscilloscope. If you are not getting proper sinusoidal wave then adjust the knobs for voltage and frequency so that you get proper sine waves which are easily readable.
Step 3: Counting voltage amplitude
- Now, count the number of vertical grids on the wave from the center of the wave. Check the readings on the volts per division i.e. voltage settings.
- Multiply this value by the number of vertical grids. This is your voltage at peak.
Step 4: Calculating current amplitude
- Count the number of horizontal grids that the wave requires to complete one period i.e. the distance between the points of the wave that are in same phase.
- Note down the readings on the knob of seconds per division setting.
- Multiply this number by the number of horizontal grids. This is the time period of the wave.
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