P5: Electricity in the home Flashcards
direct current…
flows in one direction only
alternating current…
repeatedly reverses its direction
what kind of current does home electricity use?
alternating, produces a frequency
what’s the current in homes
50Hz
what’s the voltage in homes
230V
what colour is the live wire
brown
what does the live wire do
carries the potential difference from the power supply.
what colour is the neutral wire
blue
what does the neutral wire do
completes the circuit
what colour is the earth wire
green and yellow stripes
what does the earth wire do
runs at 0V and is not part of the normal circuit. there for safety.
what do step-up transformers do?
increase pd, decrease current
what does step-down transformer do
incease current, decrease pd
why do step ups decrease current and increase pd
to reduce the resistance of the wire, and help it flow as efficiently as possible
what do we coat wires in
hard-wearing insulators, like plastic, so that heat doesn’t escape
what kind of plugs do we use
three-pin plug
why are the pins in a three-pin plug made of brass
brass is a good conductor and doesn’t rust, it is harder than copper
why are connections for wall plugs thicker than light fittings
there is more current passing through it
how does something short circuit
the live wire touches the neutral wire and a large current passes between the two wires. Fuse blows and the current turns off
why shouldn’t we touch a live wire, even when the current is turned off
our bodies have 0V, a potential difference will act across the body, lethal current will flow through them
what is power
the energy transferred to it each second.
what are the three currents of fuses
3A, 5A, 13A
what happens when charge flows through a resistor
energy is transferred to the resistor, so the resistor becomes hotter
why do all electrical appliances waste energy
the components have heating effect due to resistance, and let heat into the surroundings
