 # 4 Electric Current

This is the basic introduction to current flow and circuits. Really this unit is just an extension of GCSE Electricity with some harder problems using the same rules. Also you will need to remember how each component works and be able to interpret a VI graph. Always remember to check your gradient. Since V=IR a graph of V – y-axis and I – x-axis shows R as gradient. The other way around which is how we tend to do exp shows 1/R it does matter.

Circuit Construction Kit (phet animation)

AS Physics Unit 1_4 (lesson notes for section)

4.1 Current and charge

aluminium (Electrolysis of Aluminium Animation)

fluid_electrolysis (Electrolysis of Copper Chloride E=VIt)

4.2 Potential difference and power

Electron Speeds Worksheet (extension – challenge!)

Electricity Calculations & Sig Figures….. I would advise all of you to look at this tutorial this week before you do the unit homework…   http://www.chem.sc.edu/faculty/morgan/resources/sigfigs/index.html . An example is V = 12V, Resistance = 62Ω. If you work out the current through the resistor as V = IR changes to V/R = I = 12V/62 Ω = 0.193548A.  The original data is 2 sig figures so you should quote the answer to this as well. Hence…

0.2A  – Wrong                0.19A – Correct          0.193548A  – Wrong

4.3 Resistance

resistivity (animation) Use this to think about how atoms actually look inside a metal. Then imagine a drift of electrons through this.

4_3_Investigation (Practical Investigation & Worksheet)

4_3_Resistance Worksheet 1 (problems)

4_3_Resistance Worksheet 2(problems)

4.3 Resistance Networks Worksheet (problems)

Resistivity example data (this is a spreadsheet from practical with example graph)

Model (phet – resistivity of a wire)

Ohm’s Law Model (phet)

4.4 Components and their characteristics

4_4_Graphs Worksheet (graphing problems)

LED Forwards Bias Data (Excel) Data and graph from logger of diode in forwards bias with resistor inline.

oven temp sensor (How Science Works information sheet on thermistor at work) 