Activity 2 | Current (Adapted from PhET Colorado²)

• Go to https://phet.colorado.edu/en/simulation/circuit-construction-kit-dc and click on Download and then Run.
• Drag circuit elements from the carousel on the left into the play area. Connect them together by overlaying the dashed circles. Clicking on the connections allows you to cut them. Delete circuit elements by clicking on them and then selecting the trash can. You are encouraged to play freelyin a simulation you can't hurt anything (neither the equipment nor you!).

Click the "show current" box. Current I is merely the orderly movement of electric charges. The SI unit is the ampere which is defined as a coulomb of charge passing by in the wire every second: A = C/s. We like to imagine positive charges moving, which is the direction we define conventional current, but in normal metal wires the charges that move are actually negative electrons moving in the opposite direction. You can choose "Conventional" current with red arrows or "Electrons" which are blue circles moving the other direction. Try each and see which you prefer.

a. With the one-bulb, one-battery, two-wires circuit drag an Ammeter from the palate on the right into the play area. You can position the cross-hairs to find the value of the current at any point in the circuit. What do you notice about the current in the different circuit elements (battery, bulb, wires)?

b. What can you do to change the current? (See procedure 3 above, plus one more thing you can do to the battery.)

c. Too much current through a battery can ruin it. Figure out how to light the battery on fire.