# Rate of shifting energy down a pathway

Teaching Guidance for 14-16

## Making links between different areas of physics

It's always useful to make links between different areas of learning in physics. Whenever a student says, Oh! It's a bit like what we did before

, you have an indication of a deeper form of learning taking place. This is to be encouraged.

A useful link can be made between the power in a lighting pathway and the power in an electrical working pathway. The mathematics takes exactly the same form in each case.

For the lighting pathway:

The rate at which energy is shifted by the pathway depends on the energy shifted by each photon and on the number of photons each second. The product of these two variables gives us the power in the pathway.

For the electrical circuit:

The rate at which energy is shifted by a bulb depends on the energy shifted by each charge (the voltage) and on the quantity of charge each second (the current). The product of these two variables gives us the power in the pathway (the power output for the bulb).

Making links of this kind allows students to begin to see how different topics and ideas fit.