IB Physics 12 Mr. Jean November 5 th, 2013

The plan: Video clip of the day More on circuits Looking through components

Important to Note: Remember that by definition “Current” is the flowing from positive to negative potential. Current uses the conventional flow which is a bit unfortunate because electron flow is from the negative terminal to positive terminal.

Important to Remember: Conventional Flow talks about the “direction of the current” which is the OPPOSITE direction of the electron flow.

Key points to circuit diagram: Circuit diagrams show the connections as clearly as possible with all wires drawn neatly as straight lines. The actual layout of the components is usually quite different from the circuit diagram and this can be confusing. The secret is to concentrate on the connections, not the actual positions of components.

Purpose: A circuit diagram is useful when testing a circuit and for understanding how it works. This is similar to a force diagram for understanding dynamics.

Additional Useful Keys for Success: Make sure you use the correct symbol for each component. Draw connecting wires as straight lines. Put a 'blob' ( ) at each junction between wires. Label components such as resistors and capacitors with their values listed along side or below the circuit. The positive (+) supply should be at the top and the negative (-) supply at the bottom.

Simple Basic Circuits: –This is an example of a light and how it works in a circuit.

This is an example of a light and how it works in a circuit.

How to draw circuits: 1)Start at the source of potential energy. 2)Draw the circuit from positive (+) terminal to negative (-). 3)Electron flow (I) travels from negative terminal to the positive; however current from positive to negative. 4)Label component in the order in which they appear dictated by the electric current (I)

How to draw circuits:

Let’s add 2 resistors:

Let’s add a switch and a diode:

Let’s add a capacitor and voltmeter:

Create the following circuits: 1) Create a circuit that has a 9V battery with three resistors R 1, R 2, and R 3. 2) Create a circuit with an AC power supply, a resistor, a lamp, another resistor, a heater, and a switch. 3) Create a circuit with a battery as the power supply, a resistor, a switch, a capacitor, a diode, and another resistor.

Exchange Diagrams Have your neighbour examine your diagram. –Questions to consider. Does the diagram includes all of the necessary pieces? Does the diagram clearly indicate what is going on? Could you use this diagram to create the circuit above given the components in a lab?

Example #1: Create a circuit that has a 9V battery with three resistors R 1, R 2, and R 3.

Example #1: Create a circuit that has a 9V battery with three resistors R 1, R 2, and R 3.

Example #2: Create a circuit with an AC power supply, a resistor, a lamp, another resistor, a heater, and a switch.

Example #2: Create a circuit with an AC power supply, a resistor, a lamp, another resistor, a heater, and a switch.

Return diagram to neighbour: To do: –Respond to the questions to consider 1) Give your neighbour constructive feedback and indication of how they are doing with their diagrams. 2) Think of ways their diagrams can be improved 3) Think of things which you will take from their diagram to improve your future drawings.

Problem: 1) Draw a circuit diagram with 4 lamps, 1 capacitor, an alternating (AC) power supply, with an led dipole controlling electric flow in the clock wise direction. Let’s connect each lamp to a central wire that allows the circuit to flow when the lamp does not function.

To do: Work on Quest Assignment Work read chapters 16-18