topic 2 electricity Flashcards
What are the standard circuit symbols for a cell, battery, resistor, and bulb?
Cell: short line and long line; Battery: two or more cells; Resistor: rectangle; Bulb: circle with an X inside.
What is the difference between a series and parallel circuit?
In a series circuit, components are connected in a single loop. In a parallel circuit, components are connected in multiple branches.
What is current
Current: flow of electric charge (A)
what is voltage
energy transferred per unit charge(V)
What is Ohm’s Law?
Voltage = Current * Resistance (V = I * R).
what is resistance
the measure of how difficult it is for an electric current to flow through a material or circuit
What are the I-V characteristics of a resistor, filament lamp, and diode?
Resistor: straight line through origin; Filament lamp: curved line; Diode: current flows only in one direction.
What factors affect the resistance of a wire?
Length (longer = higher resistance), cross-sectional area (thinner = higher resistance), material, and temperature.
What happens to current in a series circuit?
Current is the same at all points in a series circuit.
What happens to voltage in a parallel circuit?
Voltage is the same across all branches in a parallel circuit.
How do you calculate total resistance in a series circuit?
Total resistance = R1 + R2 + R3 + …
How do you calculate total resistance in a parallel circuit?
1 / Total resistance = 1 / R1 + 1 / R2 + 1 / R3 + …
What is the difference between AC and DC?
AC (alternating current) changes direction; DC (direct current) flows in one direction.
What are the roles of live, neutral, and earth wires in a plug?
Live: carries current to the appliance; Neutral: completes the circuit; Earth: safety wire to prevent electric shocks.
What is the purpose of a fuse or circuit breaker?
To break the circuit if the current is too high, preventing overheating and fires.
What is the formula for electrical power?
Power = Current * Voltage (P = I * V).
What is the formula for energy transferred in a circuit?
Energy = Power * Time (E = P * t) or Energy = Current * Voltage * Time (E = I * V * t).
What is the National Grid?
A system of cables and transformers that distributes electricity from power stations to homes.
Why are step-up and step-down transformers used in the National Grid?
Step-up transformers increase voltage for efficient transmission; step-down transformers decrease voltage for safe use in homes.
