Explain how to calculate the percentage error.

To calculate percentage error, use the formula: (|Experimental Value - True Value| / True Value) × 100%.

Percentage error measures how accurate an experimental value is compared to a true or accepted value. To find it, you first need the experimental value (the value you obtained from your experiment) and the true value (the value that is generally accepted as correct).

1. **Subtract the True Value from the Experimental Value**: This gives you the error, which can be positive or negative. For example, if your experimental value is 105 and the true value is 100, the error is 105 - 100 = 5.

2. **Take the Absolute Value of the Error**: The absolute value ensures the error is always positive, as percentage error is concerned with the magnitude of the error, not its direction. In our example, the absolute error is |5| = 5.

3. **Divide the Absolute Error by the True Value**: This step normalises the error relative to the true value. Using our example, 5 / 100 = 0.05.

4. **Multiply by 100 to Convert to a Percentage**: Finally, multiply by 100 to convert the decimal to a percentage. So, 0.05 × 100 = 5%.

Therefore, the percentage error in this example is 5%. This method helps you understand how significant the error is in relation to the true value, making it easier to assess the accuracy of your experimental results.