Kirchoff's Current Law

Objectives:

• Know that the current flowing into a junction is equal to the current flowing out of a junction

• Be able to build a parallel circuit and measure the current at different points in the circuit.

• Be able to use Kirchoff's current law to solve problems involving current flow in parallel circuits.

Task 1 - Starter

Remind the person next to you:

    - how an ammeter connects into a circuit

    - how a voltmeter connects into a circuit

    - if an ammeter has a big or small resistance

    - if a voltmeter has a big or small resistance

Task 2

Your teacher will remind you how we connect components in series in parallel and demonstrate where to connect the ammeter to measure the current at different points in the circuit.  Watch carefully - you will need to do this in a minute!

Task 3

Follow these instructions to build the circuits and measure the current at each of the points specified.

In each case:

• Draw the circuit diagrams

• Measure current at each of the points specified.

• Record your results neatly in a table.

• Write a brief explanation of your findings.

Get your teacher to check your results before you pack away the equipment.

Task 4

Copy Kirchoff's first law into your book.  If you have time you can start on the homework task.

Homework/Extension:

Complete the worksheet "11_ELEC1/2" using Kirchoff's first law to find and label the missing currents.