Electricity Flashcards
(28 cards)
What two conditions are necessary for electric charge to flow through a circuit?
The circuit must be closed and there must be a source of potential difference (e.g. battery).
What is the equation for calculating charge flow?
Q = I × t where Q = charge (C), I = current (A), t = time (s).
In a closed loop, how does current behave?
The current has the same value at every point.
What equation relates current, potential difference, and resistance?
V = I × R
What happens to current as resistance increases?
Current decreases for a given potential difference.
What is an ohmic conductor?
A component where current is directly proportional to potential difference, with constant resistance.
How does a filament lamp behave as current increases?
Resistance increases due to heating.
How does a diode behave in different directions?
It conducts easily in one direction, but has high resistance in the reverse direction.
How does temperature affect resistance in thermistors?
Higher temperature = lower resistance.
How does light affect resistance in LDRs?
Higher light intensity = lower resistance.
How does length of a wire affect resistance?
Longer wire = more resistance.
In a series circuit, how is current distributed?
Current is the same throughout all components.
In a series circuit, how is voltage distributed?
It is shared between components.
In a parallel circuit, how is current distributed?
It splits between branches.
In a parallel circuit, how is potential difference distributed?
It is the same across each branch.
What is the total resistance of two resistors in parallel?
Less than the smallest individual resistor.
What is the frequency and voltage of UK mains electricity?
50 Hz and about 230 V.
What is the role of the live wire in a plug?
Carries current to the appliance at 230 V.
What is the purpose of the earth wire?
Prevents the appliance casing from becoming live.
What type of current do batteries supply?
Direct Current (DC).
What is the formula for electrical power using energy?
P = E / t
What is the formula for power using current and potential difference?
P = I × V
What is the formula for energy transferred using charge and potential difference?
E = Q × V
What is the purpose of a step-up transformer?
Increases potential difference to reduce energy loss during transmission.
