To measure the potential difference across longer sections of the circuit, we need to use a voltmeter. We can place the red probe of the voltmeter at point E, and the black probe at different points listed to measure the voltage across those points. We need to record our measured values below.
For example, to measure the voltage across points E and H, we place the red probe on E and the black probe on H, and record the voltage value. We repeat this process for other points listed and enter our measured values below.
In response to question 4, the correct answer is c. A potential difference (voltage) only exists across components that have resistance. This is why the wires, which have no resistance, do not show a voltage drop. The light bulb, on the other hand, has a resistance of 100 and therefore shows a voltage drop. So, a potential difference exists across components that have resistance, but not across all points in the circuit. The potential difference (voltage) may increase or decrease between certain points depending on the resistance of the components between those points.