1. Electricity Physics 5: Measuring Current and Voltage
Science 9
Electricity
Physics 5: Measuring Current and Voltage

2. Objectives By the end of the lesson you should be able to:
Calculate current and voltage in all circuits
Convert between Amps & milliAmps; Volts & milliVolts; Ohms & kiloOhms

3. Ammeters and Voltmeters
Ammeters are put into circuits in SERIES
Voltmeters are put into circuits in PARALLEL

4. Conversions: Amps and MilliAmps
Amps (A) are too big for many appliances so we use a smaller unit called milliAmps (mA)
There are 1000 mA in every A
So 3.5 A = 3500 mA (we moved the decimal 3 times to the right)

5. Practice Conversions:
17250 mA
610 mA
0.011 mA
1.419 A A
0.006 A
17.25 A
0.61 A A
1419 mA
37805 mA
6 mA

6. Circuit Calculations
Parallel 2 paths: IT = 300 mA and I1 = 150 mA, what is I2?
Parallel 3 paths: each path has a current of 150 mA, what is IT?
Parallel 4 paths: I1 = 1.5 A, I2 = 0.35 A, I3 = 650 mA and I4 = 5 mA, what is IT?

7. Conversions: Volts and milliVolts
Exactly the same as Amps and milliAmps!
There are 1000 mV in every V
So 7.5 V = 7500 mV (we moved the decimal 3 times to the right)
EX: 450 mV = 0.45 V
825 V = mV

8. Conversions: Ohms and kiloOhms
We will learn more about Ohms and resistance next class but…
Ohms (Ω) are too small for many appliances so we use a larger unit called kiloOhm (kΩ)
There are 1000 Ω in every kΩ
So 150 Ω = 0.15 kΩ (we moved the decimal 3 times to the left)

9. Practice Conversions:
4.67 kΩ
0.9 kΩ
56.5 kΩ
8500 Ω
900 Ω Ω
4670 Ω
900 Ω Ω
8.5 kΩ
0.9 kΩ
24.8 kΩ