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

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

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

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)

Practice Conversions: 17250 mA 610 mA 0.011 mA 1.419 A 37.805 A 0.006 A 17.25 A 0.61 A 0.000011 A 1419 mA 37805 mA 6 mA

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?

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 = 0.825 mV

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)

Practice Conversions: 4.67 kΩ 0.9 kΩ 56.5 kΩ 8500 Ω 900 Ω 24 800 Ω 4670 Ω 900 Ω 56 500 Ω 8.5 kΩ 0.9 kΩ 24.8 kΩ