PRACTICE COLLECTION / 42 PROBLEMS
Magnetism & induction
Work with moving charges and changing flux. Each problem includes progressive hints, guided reasoning and a question to test the idea again. Problems marked “Free sample” are complete for everyone; membership opens the rest.
A CONNECTED PRACTICE PATH
From field direction to induced current
Draw directions before calculating magnitudes. Move from individual charges to field superposition, then track what actually changes in a loop’s flux. Use each final transfer question to test the changed condition.
MEMBERSThis 4-stage guided path through the collection is part of membership.Unlock →
LEARN BEFORE YOU PRACTISE
Build the reasoning first.
Magnetic forces, selected velocities and current-produced fields
Use cross products for direction, circular dynamics for motion and Biot–Savart geometry for field sources.
13 worked examples · 11 checks →Induction, moving conductors and magnetic energy
Follow the changing flux, establish the sign, and close the energy account.
16 worked examples · 12 checks →Alternating circuits: phase, RMS and real power
Build the circuit response from derivatives, then use phasors and energy to check it.
9 worked examples · 8 checks →From changing electric fields to electromagnetic waves
Resolve the capacitor-gap puzzle, derive the wave speed and follow energy through the fields.
7 worked examples · 8 checks →From LC energy exchange to RLC resonance
Connect charge, current, phase and loss without confusing three different frequencies.
7 worked examples · 5 checks →Coupled coils and transformer reasoning
Track shared flux, winding polarity, stored energy and the load seen by the source.
7 worked examples · 6 checks →Magnetic moments, materials and hysteresis
Connect microscopic alignment to measurable fields, sample geometry and energy loss.
7 worked examples · 5 checks →CONCEPTS IN THIS COLLECTION
PRACTISE AT YOUR PACE
Problems in this collection
42 problems · Showing 12
Magnetism & induction
Apply the charge sign last
The cross product and the sign of the charge are two separate direction decisions.
Apply a principleMagnetism & induction
Read velocity components from a helix
What is the ratio |v_parallel|/v_perpendicular?
Read graphs & measurementsMagnetism & induction
Zero flux can still mean current
At t=3.0 s, what is the signed current? Counterclockwise viewed from +z is positive.
Apply a principleMagnetism & induction
The magnetic moment follows the coil normal
What is the torque magnitude on the coil?
Connect conceptsMagnetism & induction
The induced field opposes the change
What is the signed current if counterclockwise is positive as seen by you?
Apply a principleMagnetism & induction
A phase label must be compared with the voltage
What average real power enters the load?
Read graphs & measurementsMagnetism & induction
Maximum flux is not maximum induced emf
What is the signed induced emf at θ = π/6 for the positive circulation linked to that normal?
Connect conceptsMagnetism & induction
Two loads behind one transformer
What RMS current does the primary draw?
Connect conceptsMagnetism & induction
Heat released before the speed halves
How much heat has been released when the speed first reaches 1.5 m/s?
Connect conceptsMagnetism & induction
Check the force directions first
Find the speed for undeflected motion.
Connect conceptsMagnetism & induction
Follow changing flux across the gap
Find the displacement-current magnitude through the gap.
Connect conceptsMagnetism & induction
A moving rod can have voltage without a circuit.
What is the potential difference between the upper and lower ends in magnitude, and which end is positive?
Connect concepts12 of 42 shown