Energy and power of electricity and the national grid Flashcards
State the equation linking current, potential difference and power
Power= Current x potential difference
State the equation linking current, power and resistance
Power= current 2 x resistance
State the two most commonly wasted forms of energy
Thermal and sound
When energy is wasted what happens to it
It is dissipated into the environment
State the equation linking time power and energy
Energy=power x time
State the equation linking energy, potential difference and charge flow
Energy= Charge flow x potential difference
What is the national grid composed of ?
Cables and transformers linking power stations to consumers
What is the national grid used for
Suppling electricity to houses
State the effect of step up transformers on potential difference
Increases p.d
State the effect of step down transformers on potential difference
Decreases p.d
State the effect of step up transformers on current
Decreases current
State the effect of step down transformers on current
Increases current
Why are step up transformers used
To reduce energy loss for cables (thermal)
Why are step down transformers used
To reduce the potential difference to make it safe for domestic use
Why is the national grid efficient
Transformers reduce heat loss from wires when electricity travels long distance
If there are four times as many turns on the secondary coil as on the primary coil, then the voltage output on the secondary coil __________
will be four times the input voltage.
A transformer can change the voltage (potential difference) in wires carrying _________
alternating currents.
Step-up transformer
Ns _ Np .
>
Step-down transformer
Ns _ Np .
<
Vs=
(Vpx Ns) /Np
Ns=
(VsxNp)/Vp
Np=
(Vp/Ns)/Vs
What term is used to describe when magnetic materials become magnets in a magnetic field?
induced magnetism
What do we call a loop of wire that is coiled into a cylindrical shape?
Solenoid
