P2 - Electricity Flashcards
What is current?
The flow of electrical charge.
What is the charge of electrons? How does this affect movement in a circuit?
. Negative
. Electrons are repelled by the negative end of the cell
What is potential difference measured in? using which equipment?
Volts
Voltmeter
What is the equation for charge flow?
Charge flow (c) = current (A) x time (s)
Why is the voltmeter placed in parallel to the component?
Because the voltmeter measures the difference in the energy the electrons have before they go into the component and after they have left it.
What is the equation for energy transferred?
Energy transferred (j) = charge flow (c) x potential difference (v)
Energy transferred = power x time
What is potential difference?
The energy transferred, per coulomb of charge that passes, between two points in a circuit.
What is the equation for potential difference?
potential difference (v) = current (A) x resistance (Ω)
What is resistance?
When conductors oppose the flow of electrical current.
What is the equation for resistance?
Resistance = potential difference ÷ current
What is the national grid?
A network of cables and transformers across the country, that transfer electricity from power stations to consumers,
What is the function of a step-up transformer?
To increase the potential difference of the electricity. This reduces the current, which means less power is lost during transmission.
What is the function of a step-down transformer?
To reduce the potential difference of the electricity, which means that current increases.
What are the advantages of using overground cables for transmitting electricity?
. Cheap
. Easy to repair
. No cooling or insulation required
What are the advantages of using underground cables for transmitting electricity?
. No visual pollution
. No danger of electrocution
. Are not easily damaged
