Part C: Series and Parallel Circuits

Set up the circuit shown below, and measure the voltages across $R_1$ and $R_2$.

Read off the value of the resistors, the value of the voltage of the power supply, and predict or calculate the expected voltages across the resistors. What current flows through each resistor? Decide this from the measurements of the voltages without using an ammeter. Are the currents the same or different? Which should they be?

After this, add a third resistor in parallel with $R_2$, as shown below.

Record the value of the third resistor in your lab book, and predict what will happen to the current through the other two resistors. Will the currents through them increase, decrease, or stay the same? Try to give an answer without using an equation. Once you have thought about it and recorded an explanation, measure and record all the voltages and determine the currents through each resistor and whether or not you had the right idea.