Use a sharp pencil and a ruler. Draw circuit wires as straight lines with square corners, and use the standard symbols. Tap π See examples to see how the diagram usually looks β pictures online vary, so if one disagrees with the instructions, follow the instructions. β All key diagrams
12. Circuit symbols chart
Draw a table with two columns: “component” and “symbol”. Draw the symbols for: cell, battery, switch (open and closed), lamp, fuse, resistor, variable resistor, diode, LED, thermistor, LDR, ammeter and voltmeter. Take care with details: the long line of a cell is positive; a diode is a triangle pointing towards a bar; an LED and LDR both have two small arrows (pointing out for an LED, in for an LDR).
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13. Series circuit
Draw one loop with a battery, a switch and two lamps. Put an ammeter in the loop, in series. Draw a voltmeter connected across one lamp, in parallel. Label: “current is the same everywhere”, “p.d. from the battery is shared between the lamps”.
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14. Parallel circuit
Draw a battery with two separate branches, each containing a lamp. Put an ammeter in each branch and one in the main part of the circuit near the battery. Label: “p.d. across each branch is the same”, “total current = sum of the branch currents”, “total resistance is less than the smallest resistor”.
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15. Conduction in a metal wire
Draw a long rectangle for a section of wire. Inside, draw rows of large circles with a + sign in each (positive metal ions in a regular pattern). Between them, draw small dots with a β sign (free electrons). Draw arrows on the electrons all pointing the same way. Label: “positive metal ions”, “free (delocalised) electrons”, “electrons flow towards the positive terminal”, “current is the flow of charge”. Note: conventional current is shown from + to β, the opposite way to electron flow.
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16. Resistance of a wire practical
Draw a metre ruler with a test wire taped along it. Show a crocodile clip at the zero end and a second crocodile clip that can slide along the wire. Connect them in a circuit with a battery (or power pack), a switch and an ammeter in series. Draw a voltmeter connected across the length of wire between the clips. Label: “length of wire (independent variable)”, ammeter, voltmeter, crocodile clips.
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17. Resistance vs length graph
Draw axes with “length (cm)” on the x-axis and “resistance (Ξ©)” on the y-axis. Draw a straight line sloping upwards through the origin. Label: “straight line through the origin β resistance is directly proportional to length”.
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18. IβV graph for a resistor
Draw axes that cross in the middle of the page, with “potential difference (V)” on the x-axis and “current (A)” on the y-axis, including negative values. Draw a straight line through the origin from the bottom left to the top right. Label: “ohmic conductor β current directly proportional to p.d.; resistance is constant (at constant temperature)”.
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19. IβV graph for a filament lamp
Draw the same four-quadrant axes. Draw an S-shaped curve through the origin that gets flatter at both ends. Label: “as the current increases, the filament gets hotter and its resistance increases”.
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20. IβV graph for a diode
Draw the same axes. Along the negative p.d. side, draw the line flat along the x-axis (zero current). On the positive side, keep it flat until about 0.6 V, then draw it curving steeply upwards. Label: “very high resistance in reverse β no current” and “current flows in the forward direction only”.
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21. IβV characteristics practical circuit
Draw a battery, a variable resistor, an ammeter and the component being tested (resistor, lamp or diode) all in series. Draw a voltmeter across the component only. Label: “variable resistor β changes the p.d. across the component”, “reverse the battery connections to get negative values”.
π See examples Β· π Required practical page
22. Thermistor: resistance vs temperature
Draw axes with “temperature (Β°C)” on the x-axis and “resistance (Ξ©)” on the y-axis. Draw a curve starting high on the left and falling steeply, then levelling off. Label: “resistance decreases as temperature increases”. Draw the thermistor symbol next to the graph.
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23. LDR: resistance vs light intensity
Draw axes with “light intensity” on the x-axis and “resistance (Ξ©)” on the y-axis. Draw a curve falling steeply, then levelling off. Label: “resistance decreases as light intensity increases”. Draw the LDR symbol next to the graph.
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24. Thermistor controlling a lamp
Draw a battery, a thermistor, a lamp and an ammeter in series. Label: “as the room warms up, the thermistor’s resistance falls, the total resistance falls, so the current increases and the lamp gets brighter”. Underneath, draw the same circuit with an LDR instead and label it “brighter when light falls on the LDR”.
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25. a.c. and d.c. traces
Draw two graphs of “potential difference (V)” against “time (s)”. On the first, draw a horizontal line above the time axis and label it “direct current (d.c.) β always the same direction, e.g. a battery”. On the second, draw a smooth wave going above and below the time axis and label it “alternating current (a.c.) β changes direction, e.g. UK mains, 50 Hz, 230 V”.
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26. Three-pin plug
Draw a large rectangle for the inside of a plug with three pins at the top. Draw the earth wire going to the top pin, the live wire to the bottom right pin through a fuse, and the neutral wire to the bottom left pin. Draw a cable grip where the cable enters. Label: “earth β green and yellow”, “live β brown”, “neutral β blue”, “fuse”, “cable grip”, “plastic case (insulator)”, “brass pins (conductor)”.
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27. The National Grid
Draw a flow diagram from left to right: a power station, then a step-up transformer, then pylons and transmission cables, then a step-down transformer, then houses. Label: “step-up transformer β increases p.d., decreases current”, “high p.d., low current β less energy lost heating the cables”, “step-down transformer β decreases p.d. to about 230 V for safety”.
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28. Charging by friction (S only)
Draw a polythene rod and a cloth, before and after rubbing. Before: show an equal number of + and β signs on each. After: show extra β signs on the rod and extra + signs on the cloth. Draw a curved arrow from the cloth to the rod labelled “electrons transferred”. Label: “rod gains electrons β negatively charged”, “cloth loses electrons β positively charged”.
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29. Electric field around a charged sphere (S only)
Draw a circle with a + sign inside. Draw eight straight lines going outwards from the surface, evenly spaced like the spokes of a wheel, with arrows pointing away from the sphere. Label: “field lines point away from a positive charge”, “field is strongest close to the sphere, where the lines are closest”. Draw a second one with a β sign and arrows pointing inwards.
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Check your drawings: Electricity topic page | Components and IβV characteristics | Required practicals | Teach the topic: Electricity
