Make Electronics

Experiencing Electricity 23

Experiment 4: Varying the Voltage

It’s time now to nail this down with some numbers. Here’s one last thing to
try. Set aside the LED and substitute a 1KΩ resistor, as shown in Figure 1-64.
The total resistance in the circuit is now 1KΩ plus whatever the resistance the
potentiometer provides, depending how you set it. (The meter also has some
resistance, but it’s so low, we can ignore it.)

Amps

6v Battery Pack

Figure 1-62. To measure amps, as illustrated here and in Figure
1-63, the current has to pass through the meter. When you
increase the resistance, you restrict the current flow, and the
lower flow makes the LED glow less brightly.

6v Battery Pack

Amps

Figure 1-63