A random error is caused by unpredictable factors that affect the measurement of a variable.

Uncertainty is an estimate of how far from the true value a measurement might be. It is equal to half the range of repeat measurements.

The mean is calculated by adding each measurement and dividing by the number of measurements.

An anomalous result is a measurement that is significantly different from the others. It should be crossed out and not used in calculating the mean.

Measuring the speed of water waves from distance and time

Combined science

In the Electromagnetic waves unit, they will build on this knowledge to learn about the reflection and refraction of light, other types of electromagnetic radiation in the EM spectrum and the helpful and harmful effects of each type of radiation.

In the Waves unit, pupils learnt about the properties and propagation of transverse and longitudinal waves.

Measuring waves

Physical activity and equipment requiring safe use

Which of the following are SI (International System of Units) units of distance and time?

Which of the following is the SI unit of speed?

the type of water (i.e. how much salt it contains)

Which of the following affects the speed of a water wave?

errors can be identified and discounted or repeated

mistakes are often made with the first measurement

Why are repeat measurements taken when measuring the time it takes a water wave to travel a set distance?

What is the name given to the type of error caused by differences in a person’s reaction time? 

A result that is close to the true or expected value is {{}}.

Match the following quantities to their units.

Which of the following is the correct equation for speed?

Which of the following is not a unit of speed?

Sam take three repeat measurements for the time taken for a wave to travel a set distance. The results are 0.21 s, 0.19 s and 0.26 s. 
Calculate the mean time.
You do not need to include the units.

Random errors make repeat readings identical.

Random errors make repeat readings slightly different to each other.

Random errors make repeat readings more accurate.

Random errors make all repeat readings inaccurate by the same amount.

What effect do random errors have on repeat readings?

The uncertainty in a measured value refers to ...

Content guidance

Risk assessment required - equipment

Adult supervision required

Starter Quiz