Heat and Electricity

Beginning Activity In Pairs (Think) and discuss the meaning of each of the words that you have been given. Once you have agreed on the meaning for each of the words, write them down. Now share your words with the other groups to gain a group list. Group One Conduction Current Metal Voltage Group Two Convection Insulation Charge Reflection Group Three Radiation Energy Vibration Circuit

Construct a Venn diagram like the one below to distinguish between the words that are relevant to: (a) heat transfer (b) electrical energy transfer (c) both heat and electrical energy transfer. Heat Transfer Electrical Energy Transfer

Heat: Energy in Transit Heat is energy in transit from one region to another with a lower temperature. It is moved in 3 different ways

Conduction It’s the transfer of heat through a substance as a result of neighbouring vibrations. Particles at high temperature move faster than those in lower temperatures. (Kinetic Energy) When the more energetic particles crash into lesser energetic the kinetic energy is transferred until the temperatures are the same. Solids Liquids Gases Draw diagram

Convection In liquids and gases, heat can be transferred from one region to another by the actual movement of particles. This type of heat transfer is called convection. In solids, the particles vibrate about a fixed position and convection does not occur. When the particles heat up they then spread out and rise when they cool down the particles slow down and spread out less therefor they fall. Draw diagram

Radiation Heat can be transferred without the presence of any particles at all. E.g. Heat from the sun. Heat transferred in this way is called radiant heat. Most of it in the form of infra-red radiation. Radiant heat can be reflected, transmitted or absorbed. How much energy is reflected, transmitted or absorbed depends on the properties, including colour, of the surface. Draw diagram

Electricity in Transit A pathway in which electrical energy flows is called an…. Electric Circuit The move of electrical energy from one place to another is based the movement of electric charge. A particle that has more protons than electrons is said to be positively charged. A negatively charged particle has more electrons than protons.

Electric Circuits An electric circuit is made up of three essential parts. Power Supply Provides the electrical energy e.g. Batteries Load An electrical device that converts electrical charge in to a useful form e.g. a torch. Conducting Path A median that allows the charge to flow. e.g. a wire circuit.

Current and Voltage Current is a measure of the amount of positive electric charge passing through a particular point every second. It flows from a positive terminal to a negative Voltage is a measure of the amount of electrical energy gained or lost by the charge as it moves through a circuit.

When electric charge moves through a circuit, it gains electrical energy as it passes through the power supply + - 6V It loses the same amount of energy as it passes through the rest of the circuit.

Series and Parallel Circuits A series circuit is a circuit that has all of the components e.g. batteries, switch and globes, are all set up one after the other. + - 6V Even though it is a simple circuit, if any one part of the circuit is faulty, the connecting path is broken and nothing in the circuit will work. Identical globes in a series circuit have the same brightness because they share the voltage equally

Parallel Circuits In a parallel circuit, each component is connected in a separate conducting path. + - 6V This means that if one part of the circuit is faulty, the other parts will still work. Identical globes in a parallel circuit have the same brightness because they all have the same voltage across them and they equally share the electric current passing through the power supply.

Scale and Measurement An ammeter is used to measure the size of electric current flowing in an electric circuit. An ammeter measures electric current in or in one- thousandths of an ampere, which are called milliamperes (mA). ammeter Amperes (A) A voltmeter is used to measure the voltage gain across the terminals of a power supply or voltage drop across parts of an electric circuit. Voltage is (not surprisingly) measured in volts (V) . voltmeter Volts (V)

A Question of Resistance Electrical is a measure of how difficult it is for electrons to flow through part of a circuit. It determines how much energy is by electric charge as is moves through a circuit. have very little resistance whilst have a very high resistance. are used in electric circuits to control the voltage and current. They can have a fixed resistance or can be variable like those in volume controls. resistance lost Conductors Insulators Resistors

Working out Resistance Resistance can be defined by a simple formula 𝑅= 𝑉 𝐼 Voltage Drop Resistance Electric Current (Amps)

Example: A torch globe carrying an electric current of 200 mA with a voltage drop of 3 volts therefore has a resistance of: So using 𝑅= 𝑉 𝐼 𝑅= 𝑉 𝐼 = 3 0.2 = 15Ω You can change it around to suit eg. V = RI