4 Drawing circuit diagrams Boardworks BTEC First Applied ScienceElectric CircuitsElectricians, architects and engineers may need to draw diagrams of electric circuits.To make diagrams easier to understand, electric circuits can be drawn using symbols to represent the components.Wires are shown as straight lines.
5 Boardworks BTEC First Applied Science Electric Circuits Circuit symbolsBoardworks BTEC First Applied ScienceElectric CircuitsTeacher notesStudents will have learned these common circuit symbols at KS3, so this activity can be used as a revision exercise.You may wish to remind students that what we frequently refer to as a battery is in fact a cell. The correct definition of a battery is more than one cell connected together.
6 Boardworks BTEC First Applied Science Electric Circuits What is current?Boardworks BTEC First Applied ScienceElectric CircuitsCurrent is a measure of how much electric charge flows through a circuit. The more charge that flows, the larger the current.Current is measured using an ammeter, which must be connected in series in the circuit.The units for current are amps (A).Teacher notesIn a series circuit, all components are connected in a single circuit, one after the other.When two or more circuit components are connected in series, the same current flows through each component.
7 Boardworks BTEC First Applied Science Electric Circuits What is voltage?Boardworks BTEC First Applied ScienceElectric CircuitsVoltage is a measure of how much energy the electrons are carrying around the circuit.Voltage is measured using a voltmeter, which must be connected in parallel with a component in the circuit.The units for voltage are volts (V).Teacher notesA voltmeter is connected by a separate branch of wire, forming a parallel circuit.When two or more circuit components are connected in series, the total voltage of the supply is shared between them.
8 Current and voltage in series circuits Boardworks BTEC First Applied ScienceElectric Circuits
17 Boardworks BTEC First Applied Science Electric Circuits Ohm’s lawBoardworks BTEC First Applied ScienceElectric CircuitsOhm’s law is a formula that links voltage, current and resistance. Resistance is measured in ohms ().voltage = current × resistanceV = I × RDepending on the values given, the formula can be used to calculate voltage, current and resistance in a circuit.Teacher notesThe two other equations that can be written are:R = V/II = V/R.What two other equations could you write from this Ohm’s law formula triangle?
18 What does Ohm’s law mean? Boardworks BTEC First Applied ScienceElectric CircuitsThese three equations can be derived from the Ohm’s law formula triangle. But what do they actually mean?If the voltage increases, then either the current flowing through a material or the resistance will also be increased.V = I × RThe resistance of a material is constant for a given temperature, which means that current and voltage must be proportional.R = V/IFor a low resistance material, more current is allowed to flow for a given voltage. For a high resistance material, less current will flow at the same voltage.I = V/R
19 Ohm’s law calculations Boardworks BTEC First Applied ScienceElectric Circuits
20 Boardworks BTEC First Applied Science Electric Circuits Using Ohm’s lawBoardworks BTEC First Applied ScienceElectric CircuitsOhm’s law can be used to calculate the resistance of a component in a circuit.It is difficult to measure the resistance of a component in a circuit directly, so it is usually done by measuring the voltage and current through the component instead.Which equation would you use to calculate resistance?R = V/IWhich instrument would be used to measure the voltage?voltmeterWhich instrument would be used to measure the current?ammeter
21 Investigating resistors Boardworks BTEC First Applied ScienceElectric CircuitsTeacher notesThe coloured bands on a resistor usually denote its resistance value. However, in this activity they do not apply, as the values have been simplified.
23 Boardworks BTEC First Applied Science Electric Circuits You are an electrical engineer and have been asked to train some new employees.Prepare a handout about Ohm’s law and electric circuits.You should include the following:a brief description of how a voltmeter and ammeter are used in a circuit to measure voltage and currenta diagram of a series circuit showing how to measure the current and voltage across the battery and another componentTeacher notesThis assignment will help students to work towards P8 of the grading criteria.To meet P8, students must describe the use of measuring instruments to check values predicted by Ohm’s law in given electrical circuits.an explanation of how to use Ohm’s law to calculate resistance, current and voltage, with worked examples.
24 Boardworks BTEC First Applied Science Electric Circuits Multiple-choice quizBoardworks BTEC First Applied ScienceElectric CircuitsTeacher notesThis multiple-choice quiz can be used to check students’ learning.The Electric Circuits worksheet that accompanies this presentation can also be used as a revision or plenary exercise.