1.1 Electricity and the Electron
1.2 Electron Movement
1.3 Current Flow
We finish today with sections 4 and 5.
Here are the bullet points to remember from section 4:
- When you add more battery cells in a series, a light bulb burns with greater intensity. More "current" is flowing through the bulb.
- When we measure current, we are in effect measuring the (net) amount of electrons going past a given point at any given time.
- A "coulomb" of electrons is 6,250,000,000,000,000,000 electrons (6.25 x 1018). Discussing electrons in groups this large makes it easier for us to talk about them.
- The measure of current is called an amp (for ampere). 1 amp of current is one coulomb passing any point in a circuit per second. 1 amp = 1 coulomb per second.
- I is the abbreviation for current or number of amps. a is the abbreviation for amps. The symbol for charge or coulombs is Q. So I = Q/T.
- This section also introduces scientific notation. Especially important are micro (10-6) and milli (10-3).
- An ammeter is used to measure current.
- An ammeter needs to be connected in "series," which means that all the current has to run through it.
- the positive lead of the ammeter should connect to the positive side of the circuit and the negative lead to the negative side. In other words, "observe polarity."
- De-energize the circuit before connecting the ammeter. Then re-energize. Also de-energize before disconnecting.