Practical Skills

• When measuring any length, the ruler should be as close to the object as possible to avoid Parallax error
• Parallax error is a random error that won't be the same every time
• When measuring the extension of a spring, if it's not possible to have the ruler close to the object, set squares can be used to accurately show where it lines up on the ruler
• The resolution of a ruler or meter rule is usually 1 mm, which is the smallest difference it can measure
• When using a stopwatch, there can be a large random error due to reaction time, so it's important to always do repeats and calculate a mean
• Digital instruments will give a value on the screen, and it's important to record the reading accurately
• Analog instruments may be useful in some cases, and it's important to ensure your eye is in line with the needle to avoid Parallax error
• When using a micrometer, it usually has a smaller resolution of 0.01 mm
• Calibrating a micrometer involves closing the jaws with nothing between using the ratchet on the end
• When multiplying or dividing values that have uncertainties, convert the absolute uncertainties into percentage uncertainties and add them up
• Drawing a line of best fit on a graph allows you to find a gradient, and error bars reflect the uncertainty in the data points
• Log graphs can help find the relationship between two variables when the relationship is not known
• Interpreting a graph in terms of y = mx + c can help produce an equation to represent the data
• Reading off graphs with a log scale may require making a judgment call with values between the lines