What is electric current?

The energy stored in a battery, measured in joules The rate of flow of electric charge through a conductor, measured in amperes (A) The resistance of a wire to the flow of electrons The voltage difference between two points in a circuit

What is voltage (potential difference)?

The total charge stored in a component The energy transferred per unit of charge — the electrical 'push' driving current around a circuit The number of electrons passing a point per second The opposition to current flow in a resistor

What is Ohm's Law?

Power = Voltage × Resistance Current = Voltage + Resistance Voltage = Current × Resistance (V = IR) Resistance = Current ÷ Voltage

A 12 V battery is connected to a 4 Ω resistor. What current flows?

48 A 8 A 3 A 0.33 A

In a series circuit with two bulbs, what happens to the current as it flows through each bulb?

The current halves each time it passes through a bulb The current is the same through both bulbs — current does not get 'used up' The second bulb gets twice the current because the first slows it down Current disappears at the negative terminal and is replaced by the battery

How is a parallel circuit different from a series circuit?

In a parallel circuit, the current is the same in every branch In a parallel circuit, components share the same voltage but the current divides between branches Parallel circuits have no resistance because the current avoids resistors In a parallel circuit, components are connected end-to-end with no junctions

A fuse in a circuit melts and breaks the circuit when the current is too high. Why is this a safety feature?

Fuses increase resistance to slow down the current before it reaches appliances Excessive current can overheat wires and cause fires — the fuse breaks the circuit before damage occurs Fuses store excess electrical energy to prevent voltage spikes High current reduces voltage below safe levels, so fuses protect against low voltage

What is electrical power, and what is its unit?

Power is the total energy stored in a circuit, measured in joules Power is the resistance of a circuit, measured in ohms Power is the rate of energy transfer — P = IV — measured in watts (W) Power is the voltage multiplied by resistance, measured in volts

Why are household appliances connected in parallel rather than in series?

Series circuits use too much current for household use Parallel gives every appliance the full mains voltage and lets each be switched independently Parallel circuits require less total voltage from the supply Series circuits only work with direct current, not the mains AC supply

A 230 V household appliance draws 2 A of current. How much power does it use, and how much energy does it consume in 30 minutes?

115 W; 207,000 J 460 W; 828,000 J (828 kJ) 460 W; 13,800 J 232 W; 417,600 J