Static Electricity
Which way do field lines point around a positive point charge?
Radially outward.
What is electric current?
Rate of charge flow
Name a ferromagnetic metal.
Iron
What component in a DC motor reverses the current in the armature coil every half-turn?
The split-ring commutator.
Who formulated the three laws of motion and the universal law of gravitation?
Sir Isaac Newton.
Which particles move between materials during charging of solids by friction?
Electrons
State Ohm’s law.
V ∝ I
Which way do field lines run outside a bar magnet?
From north to south
Which mnemonic rule do you use to determine the direction of force (and thus rotation) on a current-carrying coil in a magnetic field?
Fleming’s left-hand rule.
Which scientist famously dropped balls from the Leaning Tower of Pisa to study free fall and acceleration?
Galileo Galilei.
In which setup can we find a uniform electric field?
Between two oppositely charged parallel plates.
How is total resistance in a series circuit calculated?
Added up
Which rule predicts the magnetic field direction on a current-carrying wire?
Right hand grip rule
State why a simple DC motor’s coil keeps spinning in the same direction rather than oscillating back and forth.
Force on each side is in the same rotational direction; inertia carries it through each half-turn.
Who unified electricity and magnetism into a single set of equations predicting electromagnetic waves?
James Clerk Maxwell.
On an field line pattern, how can we determine the areas with the highest field strengths?
High field line density
What is the power lost in a wire of resistance 0.45 ohms if 143C of charge flow through it in 3 seconds?
1020 W
How can you strengthen the magnetic field of a solenoid, other than increasing the current and number of turns?
Reduce the length across its central axis
If you double the magnetic field strength of the motor’s permanent magnets, what happens to the maximum turning effect (torque)?
Increases
In what year did Albert Einstein publish his special theory of relativity, introducing E=mc^2?
1905.
An electric field points to the left, where would an electron accelerate towards?
The right
An ideal 6 V battery is connected to a resistor 𝑅 in series with two identical resistors (each of resistance 𝑅) that are themselves connected in parallel. If the current through the series resistor is 0.54 A, calculate the value of 𝑅.
7.41 Ω.
What are magnetic domains?
Regions of aligned dipoles ("tiny magnets")
Name two different ways you could increase the torque produced by a simple DC motor without changing its magnetic field strength.
Increase the voltage supply and/ or number of turns of the coil
Which Shanghai-born physicist won the Nobel Prize in Physics in 1957 for discovering parity violation in weak interactions?
Tsung-Dao Lee.