What is electric current, and what is its SI unit?

The energy stored in a circuit, measured in Joules The rate of flow of electric charge, measured in Amperes The opposition to charge flow, measured in Ohms The potential difference between two points, measured in Volts

A charge of 90 Coulombs flows through a wire in 30 seconds. What is the current?

0.33 A 2 A 3 A 270 A

Which of the following best describes voltage in an electrical circuit?

The total charge stored in a circuit component The number of electrons flowing per second past a point The electrical potential difference that drives current around a circuit The rate at which energy is dissipated as heat

A resistor has a resistance of 12 Ω and a current of 2 A flows through it. What is the voltage across it?

6 V 14 V 24 V 48 V

What causes electrical resistance in a metal conductor?

Electrons moving too fast and overshooting the conductor The conductor having too few protons to carry positive charge Collisions between moving electrons and the vibrating atoms of the metal lattice Magnetic fields generated by the current opposing electron movement

How does the resistance of a metal wire change when its temperature increases?

Resistance decreases because the electrons gain more kinetic energy Resistance stays the same because Ohm's Law is always valid Resistance increases because the lattice atoms vibrate more, causing more electron collisions Resistance decreases because the conductor expands and electrons have more space

Which of the following is an example of a semiconductor material?

Copper Silicon Rubber Glass

A 60 W light bulb is connected to a 120 V supply. What current flows through it?

0.2 A 0.5 A 2 A 7,200 A

A resistor dissipates 100 W when carrying a current of 5 A. What is its resistance?

0.5 Ω 2 Ω 4 Ω 20 Ω

A 2,400 W electric kettle runs for 5 minutes. How much electrical energy does it use in kilowatt-hours (kWh)?

0.02 kWh 0.2 kWh 2.0 kWh 12 kWh

How many Joules of energy are equivalent to 1 kilowatt-hour (kWh)?

1,000 J 360,000 J 3,600,000 J (3.6 MJ) 1,000,000 J

An engineer measures 230 V across a component and calculates its resistance as 46 Ω. Which formula correctly gives the power dissipated?

P = V/R, giving 5 W P = V²/R, giving 1,150 W P = I/V, giving 0.022 W P = IR², giving 1,058 W