20 flashcards · Shared on 19 August 2026 by AtomAI Library
Flip each card to check yourself.
What is a magnetic field?
A region where a magnetic pole, moving charge, or current-carrying conductor can experience a force
What is a magnetic field?
A region where a magnetic pole, moving charge, or current-carrying conductor can experience a force
At a point in a magnetic field, what determines the field's direction?
The direction in which the north pole of a small compass points
What is the shape of the magnetic field lines around a long, straight current-carrying wire?
Concentric circles centred on the wire
How can the direction of the magnetic field around a straight current-carrying wire be found?
Use the right-hand grip rule, with the thumb pointing in the conventional current direction
When is the magnetic force on a straight current-carrying wire greatest?
When the wire is perpendicular to the magnetic field
Which equation gives the magnitude of the force on a straight wire of length L carrying current I at angle θ to a uniform magnetic field B?
F = BIL sin θ
A charged particle moves parallel to a uniform magnetic field. What magnetic force acts on it?
No magnetic force
A charged particle enters a uniform magnetic field at right angles to the field. If no other forces act, what path does it follow?
A circular path at constant speed
What happens to the magnetic field inside a long solenoid when its current is increased?
It becomes stronger while keeping the same general pattern
What is magnetic flux through a flat surface in a uniform field?
The product BA cos θ, where θ is the angle between the field and the surface normal
Which situation produces the greatest magnetic flux through a flat loop in a uniform field?
The plane of the loop is perpendicular to the field
What does Faraday's law state about induced electromotive force?
It is proportional to the rate of change of magnetic flux linkage
What does Lenz's law determine?
The direction of an induced current
According to Lenz's law, why does an induced current oppose the change that produces it?
To conserve energy
How does a simple electrical generator produce an alternating emf?
A coil rotates so that its magnetic flux linkage changes periodically
A straight conductor of length L moves at speed v perpendicular to a uniform magnetic field B. What emf is induced across it?
BLv
Why does a transformer require a changing current in its primary coil?
A changing current creates changing magnetic flux, which induces an emf in the secondary coil
For an ideal transformer, which relationship connects voltage and number of turns?
Vp/Vs = Np/Ns
In an ideal step-up transformer, how do the secondary voltage and current compare with the primary values?
Voltage is greater and current is lower
Which change can induce an emf in a conducting loop?
Moving the loop into a region where the magnetic field is stronger