Magnets and fields
What are the two poles of a magnet called, and how do they interact?
North & South. Like poles repel, opposite poles attract.
What do moving charges produce around a wire?
A magnetic field
What type of energy conversion occurs in a DC motor?
Electrical -> kinetic
What is the formula linking voltage, current, and resistance?
V = IR
What is a solenoid
A coil of current-carrying wire
What is the term for the invisible area around a magnet where magnetic forces act?
Magnetic field
What rule do we use to find the direction of the magnetic field around a current-carrying wire?
Right-hand rule
Name the part of a DC motor that reverses current direction every half turn.
Commutator
In a series circuit, what happens to the current through each component?
It remains the same
State one way to increase the magnetic field strength of a solenoid.
Increase turns per length, current, or use an iron core
Magnetic field lines flow from which pole to which pole?
From north to south
Write the formula for the force on a current-carrying wire in a magnetic field.
F = B I L
Explain how electromagnetic induction generates current.
A changing magnetic field induces a voltage
Two resistors (3 Ω and 6 Ω) are connected in parallel. What is the total resistance?
2 Ω
What happens to a charged particle moving parallel to a magnetic field?
No force acts on it. Path unchanged
On a diagram, how can you tell where a magnetic field is strongest?
Where flux lines are closest together
In the right-hand “slap rule,” what does your thumb, fingers, and palm represent?
Thumb = current, fingers = field, palm = force
What energy transformations occur inside a hydroelectric generator? (hint:3 different energies)
Gravitational potential → kinetic → electrical energy
Explain why adding more bulbs in series makes them dimmer.
Voltage is divided across each bulb, reducing energy per bulb
What type of current is produced by generators used in power stations?
AC
A bar magnet is cut in half. What happens to its magnetic poles?
Each piece forms its own north and south poles. Poles cannot be isolated.
A 0.3m wire carrying 5A runs perpendicular through a 0.4T field. What is the magnetic force on the wire?
F = BIL = 0.6N
Describe one similarity and one difference between a motor and a generator.
Both use coils and magnetic fields; motor converts electrical to motion, generator converts motion to electricity.
A circuit has 12 V and 3 A current. Calculate its resistance and power.
R = V/I = 12/3 = 4 Ω
P = V I = 12 x 3 = 36 W
Explain how a generator produces electricity.
By moving a magnet near a coil, or rotating a coil in a magnetic field, which induces a current through electromagnetic induction