© OUP: To be used solely in purchaser’s school or college Connecting circuits Circuits and current Circuits and energy Circuits summary 7J Electrical circuits

© OUP: To be used solely in purchaser’s school or college Connecting circuits 7J Electrical circuits

© OUP: To be used solely in purchaser’s school or college All electrical objects need 3 things to make them work. What are they? What must happen for the electrical device to work? 1. A power supply - like a cell (battery) or a mains supply. 2. Wires - provide a path for electrical charge to pass through. 7J Connecting circuits – Making electrical objects work 3. An electrical device - like a bulb or a motor.

© OUP: To be used solely in purchaser’s school or college When the switch is turned on, the circuit is complete. What happens to the bulb? Electrical charge flows around a complete circuit. The flow of electrical charge is called the current. What happens to the current if there is a gap in the circuit or the switch is turned off? 7J Connecting circuits – A simple circuit An electrical device only works when all the components are connected to make a complete circuit.

© OUP: To be used solely in purchaser’s school or college 7J Connecting circuits – Electrical symbols

© OUP: To be used solely in purchaser’s school or college 7J Connecting circuits – Match the symbol

© OUP: To be used solely in purchaser’s school or college 7J Connecting circuits – Switch on

© OUP: To be used solely in purchaser’s school or college 7J Connecting circuits – Circuits quiz 2.The three things needed to make a circuit are a power supply, an electrical device and… a) wires. b) a plug. c) batteries. 1.The parts that are connected to make an electrical circuit are called… a) computers. b) components. c) consonants.

© OUP: To be used solely in purchaser’s school or college 3.The flow of electrical charge around a circuit is called the… a) raisin. b) battery. c) current. 7J Connecting circuits – Circuits quiz 4. The symbol represents which electrical component? a) A switch. b) A bulb. c) An ammeter.

© OUP: To be used solely in purchaser’s school or college 6. When a switch is closed, an electrical circuit is said to be… a) complete. b) broken. c) positive. 7J Connecting circuits – Circuits quiz 5.What is the symbol for a cell? a) b) c)

© OUP: To be used solely in purchaser’s school or college 8. When a circuit is broken, what happens to the current? a) the current continues to flow. b) the current changes direction. c) the current no longer flows. 7.Batteries should be connected so that their poles are arranged… a) positive to positive. b) negative to negative. c) positive to negative. 7J Connecting circuits – Circuits quiz

© OUP: To be used solely in purchaser’s school or college Circuits and current 7J Electrical circuits

© OUP: To be used solely in purchaser’s school or college A series circuit is a continuous loop with no branches. What do the ammeter readings tell you about the current in a series circuit? 7J Circuits and current - What is a series circuit? Match each series circuit to the correct circuit diagram. A B C

© OUP: To be used solely in purchaser’s school or college Is the current used up? 7J Circuits and current – Current in a series circuit Is current the same in all parts of a series circuit? The current after the lamp and returning to the cell is also 3A. 3A The total current leaving the cell is 3A. 3A The current before the lamp is 3A. 3A

© OUP: To be used solely in purchaser’s school or college Water flowing in pipes helps to explain what happens in an electrical circuit. Why is it harder for water to flow in the narrow pipe? 7J Circuits and current - Series circuits and the water model Which parts of the water model match the electrical components? valve (open) water pump narrow pipe (harder for the water to flow)

© OUP: To be used solely in purchaser’s school or college The narrow pipe resists the flow of water. Electrical components can resist the flow of current. These are called resistors. 7J Circuits and current - Series circuits and the water model valve (open) water pump narrow pipe Where is there resistance in this electrical circuit? The thin wires in a filament bulb resist the current. How do they show resistance?

© OUP: To be used solely in purchaser’s school or college Both these circuits have the same number of batteries. Why do the ammeters show different current readings? Which component has the greater resistance? There is less current in circuit E which means it's harder for the current to flow in the circuit with the motor. 7J Circuits and current - Resistance DE

© OUP: To be used solely in purchaser’s school or college A parallel circuit contains branches with more than one route for the current. Where are the two routes in this parallel circuit? Will the current be the same in all parts of a parallel circuit? 7J Circuits and current - What is a parallel circuit? Route 1 Route 2 At a junction point the current can divide between the two routes. junction point

© OUP: To be used solely in purchaser’s school or college Is current the same in all parts of a parallel circuit? 7J Circuits and current – Current in a parallel circuit The total current leaving the cell is 3A. 3A The current returning to the cell is 3A. Is the current used up? 3A 1.5A This 3A divides up so that 1.5A goes on route 1 and the other 1.5A goes on route A

© OUP: To be used solely in purchaser’s school or college The water valves act like switches in the circuit. What happens to the flow of water when a valve is closed? What happens to the current in the matching part of the parallel circuit? 7J Circuits and current - Parallel circuits and the water model The water model can also help to explain what happens in a parallel circuit. water pump

© OUP: To be used solely in purchaser’s school or college Circuits and energy 7J Electrical circuits

© OUP: To be used solely in purchaser’s school or college A battery is an energy source that stores chemical energy. electrical energy in circuit What happens to this energy in an electrical circuit? chemical energy in battery 7J Circuits and energy - What do batteries do? What happens to the electrical energy in this circuit?

© OUP: To be used solely in purchaser’s school or college Electrical energy is used up and converted into other types of energy in the circuit. Why don’t batteries last forever? movement energy in motor light and heat energy in bulb 7J Circuits and energy - Why don't batteries last forever? Complete these energy transformations: electrical energy in circuit electrical energy in circuit motor bulb Current transfers energy to different parts of a circuit.

© OUP: To be used solely in purchaser’s school or college A battery gives current a "push" around a circuit. In which circuit does the bulb shine brightest and why? Is the current affected by the voltage? 7J Circuits and energy - Increasing voltage FGH The amount of "push" from the battery is the voltage.

© OUP: To be used solely in purchaser’s school or college Circuits summary 7J Electrical circuits

© OUP: To be used solely in purchaser’s school or college 7J Circuits summary – Build a circuit Build a circuit

© OUP: To be used solely in purchaser’s school or college 5. A parallel circuit contains branches with more than one route for the current. TRUE! True or False? Click on the box to start the quiz 7J Circuits summary – True or false? 2.The current in a series circuit is different in some parts of the circuit. FALSE! Current is the same in all parts of a series circuit. 8. Current and energy are used up in a circuit. FALSE! Only energy is used up in a circuit, current is not used up. 8.Current and energy are used up in a circuit. 3.Add an extra bulb to a series circuit and the current increases. 2.The current in a series circuit is different in some parts of the circuit. 6.The current in the branches of a parallel circuit adds up to the total current. TRUE! 4. An electrical component with a high resistance makes it easy for current to flow. FALSE! An electrical component with a high resistance makes it difficult for current to flow. 4. An electrical component with a high resistance makes it easy for current to flow. 5. A parallel circuit contains branches with more than one route for the current. 3.Add an extra bulb to a series circuit and the current increases. TRUE! 6. The current in the branches of a parallel circuit adds up to the total current. 1.Current is measured with an ammeter. The units of current are lamps. FALSE! The units of current are amps, which is short for amperes. 7. A battery converts electrical energy into stored chemical energy. FALSE! A battery converts stored chemical energy into electrical energy. 1. Current is measured with an ammeter. The units of current are lamps. 7.A battery converts electrical energy into stored chemical energy.