A solar cell is a device that can generate electrical power when light falls on it. You are given a solar cell connected to a fixed resistor as in the incomplete circuit shown in [Figure 4.1]. Plan an experiment to investigate how the brightness of the light falling on the solar cell affects the electrical power output of the solar cell. The power of the cell can be found using the equation shown. power = current × voltage The following apparatus is available in addition to the apparatus shown in the circuit diagram: • a lamp connected to a power supply • a metre rule • a voltmeter • an ammeter • connecting leads. Other apparatus normally available in a school laboratory can also be used. You are not required to do this experiment. In your plan, you should: • explain how you will vary the brightness of the light falling on the solar cell • show how the voltmeter and ammeter are used. You may draw on Fig. 4.1 to help your explanation • state any variable(s) that you will control • draw a table with column headings to show how to display recorded measurements (you are not required to enter any readings in the table) • explain how to use your measurements to reach a conclusion.