4. Electricity Flashcards
What is electric current?
The flow of electric charge
I = Q / t
Current (A) = Charge (Coulombs) / Time (seconds)
V = E / Q
Potential difference (V) = Energy transferred (J) / Charge (C)
V = I x R
Potential difference = Current x Resistance
P = E / t
Power (Watts) = Energy transferred (J) / Time (seconds)
P = I x V
Power = Current x potential difference
E = V x Q
Energy transferred (J) = Potential difference x Charge (C)
E = P x t
Energy transferred = Power x Time
Vp / Vs = Np / Ns
Voltage across primary coil / Voltage across secondary coil = number of turns on the primary coil / number of turns on the secondary coil
Vp x Ip = Vs x Is
Voltage across 1st coil x Current in primary coil = Voltage across 2nd coil x Current in secondary coil
For components in series:
The total resistance is the sum of the resistance of each component
Same current through each component
Total potential difference of the supply is shared between the components
For components in parallel:
The potential difference across each component is the same
The total current through the whole circuit is the sum of the currents through the separate components
The current through a component depends on what?
The resistance,
the greater the resistance the smaller the current for a given potential
Directly proportional to the potential difference across the resistor
What is Power?
The rate at which electricity is transferred
For a given power what does increasing the voltage do?
Reduces current required and this reduces energy lost in the cables
