Year 9 Science - Electricity Revision Booklet PDF

**[Year 9 Science: Electricity ]** **Chapter 10 of Jacaranda Science Quest 9 Textbook** **[Electricity Glossary:\ ]** **Key Word** **Definition (and examples where appropriate)** -------- ---------------------------------------------...

**[Year 9 Science: Electricity ]** **Chapter 10 of Jacaranda Science Quest 9 Textbook** **[Electricity Glossary:\ ]** **Key Word** **Definition (and examples where appropriate)** -------- --------------------------------------------------------------- ------------------------------------------------- **1** **Electricity** **2** **Electron** **3** **Static Electricity** **4** **Neutral / uncharged** **5** **Current electricity** **6** **Electric circuit** **7** **Power source** *(eg. battery)* **8** **Energy user / load** *(eg. appliance such as a light bulb)* **9** **Connecting wires** **10** **Switch** **11** **Series circuit** **12** **Parallel circuit** **13** **Voltage** **14** **Voltage drop** **15** **Volts** **16** **Voltmeter** **17** **Current** **18** **Amperes (amps)** **19** **Ammeter** **20** **Resistance** **21** **Ohms** **22** **Ohm's Law** **23** **Conductor** **24** **Insulator** **25** **Resistor** **26** **Diode** **27** **Alternating current (AC)** **28** **Direct current (DC)** **29** **Fuse** **30** **Circuit breaker** **31** **Safety switch (RCD)** **32** **Earthing** **33** **Double insulation** **Electricity Revision Activities & Questions:** 1. **[True or False:]** fill out the table below by writing whether each statement about electricity is 'true' or 'false'. **Statement:** **True or False?** ---------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------- Electricity is generated through the movement of electrons. Static electricity is a type of electricity that describes the flow of electrons around a circuit. Current electricity is generated when two neutral objects are rubbed together, creating an imbalance of negatively charged electrons on one surface or object. For current to flow around a circuit -- therefore allowing appliances such as speakers to work -- a circuit must be CLOSED. Wood is an example of a conductor. An insulator is a material that has HIGH resistance to electric current. 2. **For each of the circuit components in the table below, draw their corresponding circuit symbol and explain their function in a circuit.** **Circuit component** **Circuit symbol** **Function of component in circuit** ------------------------------------------------------------------ -------------------- -------------------------------------- Battery *(also label positive and negative terminal of battery)* Light globe Connecting wire Switch (open) Switch (closed) Voltmeter Ammeter Resistor Variable resistor Diode Fuse 3. **[Fill-in-the-blanks:]** Explain how the **flow of electricity can be compared to the flow of water through a hose** by filling in the blanks in the sentences below using the five words in the text box below: Think of a water hose. Your water hose itself is like a \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.\ \ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ can be compared to water pressure at the tap when you turn the tap on.\ \ The amount of water that flows through a hose can be compared to electrical \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.\ \ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is like a kink in your hose restricting the flow of water or something blocking the flow of water through the hose. The more resistance there is in a circuit, the more energy (voltage) is \_\_\_\_\_\_\_\_\_\_\_\_\_. 4. **Label the pins** of the household plug with the **'active', 'earth' and 'neutral'** labels in the correct spots. Then **explain what colours an 'active', 'earth' and 'neutral' wire would be** in Australia.\  5. **Match the electrical safety feature to the correct function** by drawing arrows in the space below. **Electrical safety feature** **Function** ---------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Fuse A switch that automatically turns off the current in a circuit if the current gets too large. When this happens, it switches 'off'. Each of these switches controls a different circuit. Circuit breaker or Safety switch A pin in a plug through which the electric current will flow via to the ground in the case of an electrical fault. Earthing A short length of conducting wire or a strip of metal that melts when the current through it reaches a certain value, breaking the circuit thereby preventing the flow of current. Double insulation Two levels of insulating materials (such as rubber or plastic) between electrical parts of the appliance and outer parts you touch. 6. Draw circuits based on the specifications in each row of the table below. +-----------------------------------+-----------------------------------+ | **Circuit components | **Circuit diagram** | | (specifications)** | | +===================================+===================================+ | A **series circuit** with: | | | | | | -a battery | | | | | | -two light globes | | | | | | -connecting wires | | +-----------------------------------+-----------------------------------+ | A **series circuit** with: | | | | | | -a battery | | | | | | -a closed switch | | | | | | -an ammeter | | | | | | -one light globe | | | | | | -connecting wires | | +-----------------------------------+-----------------------------------+ | A **series circuit** with: | | | | | | -a battery | | | | | | -two light globes | | | | | | -connecting wires | | | | | | -a resistor | | +-----------------------------------+-----------------------------------+ | A **parallel circuit** with: | | | | | | -a battery | | | | | | -two light globes | | | | | | -connecting wires | | | | | | -an open switch | | +-----------------------------------+-----------------------------------+ | A **parallel circuit** with: | | | | | | -a battery | | | | | | -two light globes | | | | | | -connecting wires | | | | | | -an open switch | | | | | | -a voltmeter | | +-----------------------------------+-----------------------------------+ | A **parallel circuit** with: | | | | | | -a battery | | | | | | -three light globes | | | | | | -connecting wires | | | | | | -a voltmeter | | | | | | -a fuse | | +-----------------------------------+-----------------------------------+ 7. Practice using **Ohm's Law** and solve the problems below to **determine either VOLTAGE (V), CURRENT (I) or RESISTANCE (R).** Show your working out for each problem and ensure you are writing the correct units of measurement.  a. A circuit has a resistance of 20 ohms and a current of 2 amperes. What is the voltage across the circuit?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ b. If a resistor has a voltage drop of 12 volts and a resistance of 4 ohms, what is the current flowing through it?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ c. In a circuit, the voltage is 24 volts, and the current is 3 amperes. Calculate the resistance of the circuit.\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ d. A 10-ohm resistor is connected to a 12-volt battery. What is the current flowing through the resistor?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ e. Given a current of 0.5 amperes and a voltage of 6 volts, what is the resistance in the circuit?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ f. A circuit has a resistance of 30 ohms, and the current is 0.5 amperes. Calculate the voltage across the circuit.\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ g. If a light bulb has a resistance of 60 ohms and is connected to a 120-volt power source, what is the current passing through the bulb?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ h. In a circuit, the voltage is 9 volts, and the resistance is 18 ohms. Calculate the current in the circuit.\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ i. A 15-ohm resistor is connected to a 10-volt power source. What is the current through the resistor?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ j. Given a current of 1 ampere and a resistance of 8 ohms, what is the voltage drop across the resistor?\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\ \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ **[Year 9 Science -- Summary Notes -- Electricity]** *Summarised from Chapter 10 of Jacaranda Science 9 for the Victorian Curriculum* +-----------------------------------+-----------------------------------+ | **Topics to revise** | **Have I revised this topic and | | | feel confident in it?** | +===================================+===================================+ | **[Electricity & | | | Charge:]** | | | | | | 1. Static electricity | | | | | | 2. Current electricity | | +-----------------------------------+-----------------------------------+ | **[Electric | | | Circuits]** | | | | | | 1. **Components of circuits & | | | circuit symbols** | | | | | | 2. **Series circuits** | | | | | | 3. **Parallel circuits\ | | | ** | | +-----------------------------------+-----------------------------------+ | **[Voltage, current & | | | resistance:]** | | | | | | 1. **What is voltage?** | | | | | | 2. **What is current?\ | | | -including types of current | | | (AC and DC)** | | | | | | 3. **What is resistance?** | | | | | | 4. **Ohm's Law** | | +-----------------------------------+-----------------------------------+ | **[Household Electricity & | | | Safety:]** | | | | | | 1. **Household electricity -- | | | wires, plugs, power points** | | | | | | 2. **Electrical safety features | | | (fuses, circuit breakers & | | | safety switches, earthing, | | | double insulation)** | | +-----------------------------------+-----------------------------------+ | Read through the summary notes | | | for each of the **Topics to | | | revise**. Highlight key | | | words/sections. Write down any | | | questions that occur to you | | | whenever you read something that | | | you're unsure of or that you | | | don't understand. Ask your | | | teacher to help you understand | | | these questions. | | +-----------------------------------+-----------------------------------+ **[Static Electricity & Charge:]** - Electricity is the presence and flow of electrons (hence why it is called 'elec'-tricity). - Electricity is produced when NEGATIVE electrons and POSITIVE protons are separated and re-united. - There are two types of electricity:\ -static electricity\ -current electricity - **STATIC ELECTRICITY (or electrostatic charge)** is the build-up of charge (**+** or **-**) on an uncharged (neutral) object or surface. - When we rub two neutral objects together, electrons **move between the two objects**: one object gains electrons (becomes **[negatively]** charged) and the other loses electrons (becomes **[positively]** charged). - **Static electricity or electrostatic charge** is created when there's an imbalance (build up) of charge on objects (e.g. rubbing your shoes on carpet to build static electricity in your body then zapping someone, rubbing a balloon on your hair). - **ELECTRIC CURRENT** is the movement of **negatively charged electrons** along a wire around an **electric circuit.** **[Electric Circuits:]** - An **ELECTRIC CIRCUIT** is a closed pathway that electric current can travel through. - An electric circuit is a structure or pathway through which electric current can move. - Electrical circuits can be simple or complex, but they must all have these three components: 1. A power source (e.g. a battery) *-- to supply energy to electrons which are then able to flow around the circuit to create electric current.* 2. A load (an energy user, like a light bulb) *-- to transform electrical energy in electrons into other forms of energy such as light, heat or sound energy depending on the appliance.* 3. Connecting wires (to carry electric current) *-- to act as pathways for electrons to travel around the circuit on.* - Many devices also have 'gaps' or 'breaks' in their circuits called **SWITCHES** to control the flow of electricity and regulate voltage. Switches can be open or closed:\ -an open switch means there is a gap in the circuit and current cannot flow around the entire circuit.\ -a closed switch means there is NO gap in the circuit so current flows uninterrupted around the circuit. - There are two types of electric circuits: **SERIES and PARALLEL circuits**. - In a **series circuit**, the components (such as a light bulb) are connected one after another along a single conducting pathway. - If there is a break in the circuit, there will be no current in any part of the circuit and all the globes in the circuit will be affected (turn off). - In a **parallel circuit,** each component (e.g. light globe) is **separately connected** to the energy source of a circuit in a separate conducting path. - This means that if one load or component of the circuit is faulty, the other load(s) will still work (i.e. parallel circuits are more reliable hence why they are used to wire our homes). **[Voltage, Current & Resistance:]** +-----------------+-----------------+-----------------+-----------------+ | | **Voltage** | **Current** | **Resistance** | +=================+=================+=================+=================+ | **Definition** | **Voltage: a | **Current:** | **Resistance: a | | | measure of the | **the flow and | measure of how | | | amount of force | movement of | difficult it is | | | (or pushing | electrically | for electrons | | | power) needed | charged | to pass through | | | to move | particles | a material or | | | electrons | (electrons) | component of a | | | around a | around a | circuit.** | | | circuit.** | circuit.** | | | | | | | | | *Voltage drop: | | | | | the difference | | | | | in energy the | | | | | electrical | | | | | charges carry | | | | | before and | | | | | after passing | | | | | through the | | | | | load in a | | | | | circuit (e.g. | | | | | speaker or | | | | | globe).* | | | +-----------------+-----------------+-----------------+-----------------+ | **Unit of | Volts (V) | Amperes (A) | Ohms (13,788 | | measurement** | | | Omega Symbol | | | | | Images, Stock | | | | | Photos, 3D | | | | | objects, & | | | | | Vectors \| | | | | | Shutterstock) | +-----------------+-----------------+-----------------+-----------------+ | **Circuit |  | | | Description | in it | | | | automatically | Description | | | | generated](medi | automatically | | | | a/image9.png) | generated | | | | | | | | | Voltmeter | Ammeter | | +-----------------+-----------------+-----------------+-----------------+ | **Instrument | Voltmeter | Ammeter | Multimeter | | used to | (attached in | (connected in | | | measure** | parallel) | series) | | +-----------------+-----------------+-----------------+-----------------+ | **Analogy** | **[Voltage]{.un | **The |.underline} | | | = variable | amount of water | = a kink in | | | water pressure | that flows | your hose | | | at the tap when | through a hose | restricting the | | | you turn the | can be compared | flow of water | | | tap on.** | to [electrical | or something | | | | current]{.under | blocking the | | | | line}.** | flow of water | | | | | through the | | | | | hose.** | +-----------------+-----------------+-----------------+-----------------+ - There are two types of current: **alternating current (AC) and direct current (DC).** - Alternating current (AC): form of electrical current that changes direction 50 times every second. AC is used for power supplies where you plug appliances in. - Direct current (DC): form of electrical current where current flows in one direction only. This current is found in battery powered circuits. - Ohm's Law describes the relationship between voltage, current and resistance. - Put simply, Ohm's law states if you:\ -double the voltage, you double the current\ -double the resistance, you halve the current - Ohm's Law is written as: **V = IR\ -V = voltage drop in volts (V)\ -I = current in amperes (A)\ -R = resistance in Ohm's** **[Household Electricity & Safety:]** - The electrical circuit in a house is one large **parallel circuit**, with energy user such as a light or power point on its own conducting pathway that receives **240 volts of AC (alternating current)**. - Electrical cables and wiring that feed electricity to power points in our homes are made up of three separate wires: 1. The **active** or **live** wire (coated in brown or red) carries current to the power point. 2. The **neutral** wire (coated in blue or black) carries current away from the power point. 3. The **earth** wire (coated in green and yellow) connects the power point (and any metal part of an appliance) to the earth beneath you. - In Australia, we use power points that have 2 or 3 sockets: a **neutral** socket, an **active** socket (and an **earth** socket). - Our plugs have 2 or 3 pins: a **neutral** pin, an **active** pin (and an **earth** pin). - Even a small electrical current passing through you can be deadly! Abnormally high currents can:\ -melt plastic coatings on wires and cause appliances to fail or stop working\ -set fire to fluff/dust around wiring (causing electrical fires)\ -pass through you (**electrocution**!) - There are a number of electrical safety measures that are in place to protect us from electrical faults summarised in the table below: **Electrical safety feature** **Function / what is it?** **Image / diagram** ----------------------------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------- *Fuse* A short length of conducting wire or a strip of metal that melts when the current through it reaches a certain value, breaking the circuit.  *Circuit breaker & safety switch (RCD)* Is a switch that automatically turns off the current in a circuit if the current gets too large. When this happens, it switches 'off'. Each circuit breaker controls a different circuit. Difference Between Circuit Breakers and Safety Switches *Earthing* A pin in a plug through which the electric current will flow via to the ground in the case of an electrical fault.  *Double Insulation* Two levels of insulating materials (such as rubber or plastic) between electrical parts of the appliance and outer parts you touch. China 25mm 95mm2 PVC Cable Double Insulation Wire - China Double PVC Wire, 25mm2 Electrical Wire