# Using Electricity

 What kind of appliances usually have high power ratings? Appliances which give out heat What is the purpose of a fuse? To protect the flex. What colour is the live wire? Brown What colour is the neutral wire? Blue What colour is the earth wire? Green and Yellow Where are the wires located in a plug? The BRown wire goes in the Bottom Right The BLue wire goes in the Bottom LeftThe green and yellow wire goes in the top What does the live wire do? Carries the electrical energy to the appliance What does the neutral wire do? Complete the ciruit What does the earth wire do? Acts as a safety device When might appliances not require an earth wire? If they have the double insulation symbol Why is it dangerous if the live and neutral are reversed in a plug? As if the appliance is off or the circuit is broken the appliance is still live!! What is direct current? Current that flows in one direction The mains supply is ____? a.c A battery supply is _____? d.c What is the mains voltage? 230V Electrons are _______ to move in a conductor? free What do we measure current in? Amperes (A) What do we measure voltage in? Volts (V) What do we measure resistance in? Ohms (Ω) How do we link voltage, current and resistance together? V = IR What is charge measured in? Coulombs (C) What is the formula for charge? Q = It The current in a series ciruit is ________ at all points? the same In a parallel circuit, the sum of the currents in the parallel branches is ______ to the current drawn from the supply? equal In a series circuit, the sum of the voltages across the components is ________ to the voltage of the supply? equal In a parallel circuit, the voltage across each branch is ______? the same How do you work out resistance in a series circuit? Rs = R1 + R2 + R3 ..... How do you work out resistance in a parallel circuit? 1/Rp = 1/R1 + 1/R2 ..... What is an open ciruit? A circuit with a loose or broken wire. The open circuit resistance on an ohmmeter shows ∞ Ω What is a short circuit? A circuit with two wires touching or being crossed by a loose wire. Short circuit resistance = 0 Ω In a filament lamp the energy transformation takes place in the _____? wire In a discharge tube the energy transformation takes place in the _____? gas Why is the discharge tube more effecient than the filament lamp? As more energy is transformed into light The energy transformation in an electric heater takes place in the ______? element What are the advantages of using a ring main circuit instead of a lighting circuit? Carries more currentUses less copper - so is less expensive Why may a circuit breaker be used instead of a fuse? They are easy to reset Cannot replace them with the wrong value (danger of a fuse)They are more sensitive - they flip quickly A ________ exists around a current carrying wire? magnetic field What is the purpose of brushes in a motor? They allow electrical connection to a moving contact Why are carbon brushes good? They are cheap, good conductorsThey are easily replaced if they wear away completely What is the purpose of the commutator in a motor? It keeps the motor turning in one direction Why are multi-section commutators good? They make the motor smoother and more powerful Why are stationary field coils good? They make the motor lighter and cheaper How can you turn the motor quicker? Increase:the size of the currentthe number of turns of the coilthe magnetic field strength Give two examples of uses of electromagnets Electric BellRelay Switch AuthorAnonymous ID62887 Card SetUsing Electricity DescriptionStandard Grade Physics - Using Electricity Updated2011-01-30T11:11:46Z Show Answers