Electricity and magnetism word map Write these words in the correct place on the word map, analogue electricity electric circuits permanent power series, Electricity and magnetism conductors electricity in y the home types parallel circuit symbols/diagrams current, voltage and resistance production Magnetism magnets electromagnet applications Voltage Read the text and fill in the gaps in the sentences with these words. circuit electrons force negative parallel- positive potential symbol voltage (x2) voltmeter unit Voltage is the 1_,_that pushes electrons through the electrical circuit. The greater the force (voltage) the greater the number of 2 „_that pass through the circuit in one second. That is, a larger 3_will increase the flow of electrons (current) through the 4.........__,__The change in voltage between any two points in a circuit is called the 5__,_difference between those points. The voltage can be measured using a 6_.__The voltmeter must always be connected in 7___to the appliance or component in the circuit across which it will measure the voltage. Also the 8 .................._._terminal of the voltmeter should connect to the wires coming from the negative terminal of the battery and the 9___terminal to the positive terminal of a battery. Voltage (potential difference) is given the 10 ___V. The 11_of voltage is the volt which has the symbol V. Cells and batteries available on the market usually have a 12___of between 1.5 and 12 volts (1.5-12 V). Look at the symbols and label them with the correct component. Thenadd the correct explanafciofT of each component. Component a ammeter b bulb c cell (one) and battery (more than one cell) d connecting wires e fuse f resistor g switch h transformer i voltmeter Symbol I I crossed joined Explanation j Gives out heat and light when current. passes. The second symbol represents a bulb in a holder, k Limits or controls the amount of current that passes through a circuit. ! Measures the ability of the battery to push electrons through the circuit (voltage). m Measures the rate of flow of electric current passing through a circuit or part of a circuit. n The long line is the positive terminal and the short line is the negative terminal. o Used to turn current on and off. p Usually made of copper which is a good conductor, and insulated with plastic. Wires that connect different parts of a circuit are often marked with a dot where they join, to distinguish them from wires that cross without joining. q Consists of a thin metal wire that melts to break the circuit if too much electric current passes. Helps protect electrical appliances. r Increases or decreases the voltage of electric current passing through a circuit. V -fixed -^^^*y^—- variable 8 Circuits Read the text and sort the sentences under the correct illustrations. Series circuit Parallel circuit , □ 5 1_ 2 □ 6 U 3 □ 4 □ 7 □ 8 C______1 9 □ When there are several components in an electric circuit, they can be connected in series or in parallel. a all the components in the circuit are connected together in one loop and there is only one route through which the current can traveL b Also a defective or disconnected component in one part of a parallel circuit will not stop the flow of current to the remaining branches in the circuit, c If one of the components should become defective or disconnected, no electric current will flow through the circuit, d In a parallel circuit, e In a series circuit, f The current need not be the same in each of the branches, g The same current will flow through each part of the circuit. h there is more than one route through which current can travel around and back to the battery, i Therefore the current 'splits up' to supply each branch of the circuit with electric current. Listen to the text. doubled current ratio resistor directly proportional Ohm's law doubted voltage In 1826 the scientist Georg Simon Ohm carried out experiments in which he varied the voltage across a | J and measured the current flowing through it. He found that the current which flowed was f J to the voltage across the resistor. This means that if the voltage is ( J, the current is ^___ ^_____I; if the voltage is reduced to one quarter, the current is reduced to one quarter, and so on. This result is now known as j j - It states that at a fixed temperature the current flowing in a resistor is directly proportional to the f ^ ^ __j across it. The (" ! of the voltage to the current V/I is called the resistance. Its unit is the ohm and its symbol is SI (the Greek letter omega). In SI units, a voltage of one volt across a resistance of one ohm produces a[______________j of one ampere. Saving electricity Match the beginnings and endings of the sentences. Beginnings 1 Install ceiling and wail insulation and keep curtains closed during winter 2 Use awnings to shade windows 3 Turn off appliances, including lights, 4 Set the fans of air conditioners at high speed 5 Avoid opening the fridge door too much 6 Defrost the freezer before the ice builds up 7 Only use the dishwasher when there is a full load, 8 Use cooking pots and kettles with flat, wide bottoms 9 Keep lids on pans, pots and kettles while they are in use 10 Do not open the oven door regularly while in use 11 The oven and hot plates can be turned off before cooking is finished, 12 When boiling water, 13 Use fluorescent tubes and lights instead of incandescent light bulbs. Endings a as cooler air will enter from outside, b as the ice prevents the efficient transfer of heat. c as the washer does not use less energy for smaller loads, d as these will use the heat most efficiently, e as this increases the amount of energy required to cool the inside, f because they use only one-quarter of the electricity and last up to four times longer, g do not boil more water than you need, h for greater efficiency, i so that heat does not escape into the air. j to make use of the residua! heat, k to reduce heat gain in rooms that are being cooled. I to reduce heat loss, m when they are not in use. iD 2D sQ 4Q 5O eCH 7CJ 9D ioD 11 ED 12ED 13 Electric current Read the text and sort the different materials into the table. All things on Earth are made up of tiny particles called atoms. There are many kinds of atoms, but they ail consist of 3 dense central structure called the nucleus around which negatively charged particles called electrons orbit. The flow of these negatively charged electrons within a materia! is called an electric current. Not all materials conduct electricity. Substances such as metals and graphite, a form of carbon, have some electrons that can move freely between atoms. This means they can flow as an electric current through the materials. These substances are called electrical conductors. Metals such as copper and aluminium are excellent conductors of electricity and so are commonly used to make electrical wires. Some materials, such as paper, plastic, rubber and glass, do not allow an electric current to pass through them because their electrons are unable to move around freely. These materials are called insulators or non-conductors. Electrolytes are substances which contain charged particles called ions. When they are in solution or molten, they are free to move around and can carry an electric current. Sodium chloride (common salt) solution is an example of an electrolyte. Many of our body fluids are electrolytes, which is why the human body is a good conductor of electric current. We can get an electric shock if we touch an electric current so that it flows through our bodies. Conductors Insulators Electrolytes HOMEWORK Choose the correct answers. Then dick 'check' to see if you are correct. ■ O trse Potential difference of an electric current. ! j Q measures electricity Q the amount of flow of an electric current. Q electrical power. t f\ produces light when connected to an (electridty supply. 10 supplies something, such as a car, with elect deity. ■ O ti1at measures the temperature of something, i j G the continuous movement of something. i Q changes the voltage of a flow of electricity. io reduces the heat, cold or sound that can pass through it. ! does not allow an electric current to pass j ; ^ through it. | that uses the Sun's energy to produce electricity. o the complete path that an electric current : /r~\ that controls the temperature in a building or ^ engine. flows around. (3 a flow of electricity. O resistance in an electrical circuit. Q the amount of flow of an electric current. {J) electrical power.