Magnetic Effect on current-carrying conductor
What happens around a wire when current flows through it?
A magnetic field is produced around the wire.
What happens when a current-carrying wire is placed in a magnetic field?
It experiences a force.
What energy change happens in a DC motor?
Electrical energy → Kinetic/Mechanical energy
What is electromagnetic induction?
The production of an emf (or current) when a conductor cuts magnetic field lines.
What type of current do transformers work with?
Alternating current (AC).
What rule helps you determine the direction of the magnetic field around a straight conductor?
Right-hand grip rule
What rule is used to find the direction of the force on the wire?
Fleming’s left-hand rule.
What energy change happens in an AC generator?
Kinetic/Mechanical energy → Electrical energy.
State Faraday’s law.
The induced emf is proportional to the rate of change of magnetic flux.
State the transformer equation.
Vp / Vs = Np / Ns
How does increasing current affect the strength of the magnetic field?
The magnetic field becomes stronger.
Name the factors that affect the size of the force.
Magnetic field strength, current, and length of conductor.
What part of a DC motor ensures the current direction in the coil reverses every half turn?
The commutator (split-ring).
State Lenz’s law.
The induced current flows in a direction that opposes the change producing it.
What is the purpose of a step-up transformer in power transmission?
To increase voltage and reduce energy loss in transmission lines.
What shape does the magnetic field around a solenoid resemble?
It’s similar to the field of a bar magnet.
In what condition will the force be maximum?
When the conductor is perpendicular to the magnetic field.
Why is the current in a generator alternating?
Because the coil cuts magnetic field lines in opposite directions as it rotates.
Why is no emf induced when the magnet and coil are stationary relative to each other?
Because there is no change in magnetic flux.
Why is energy lost in transmission lines?
Due to heating from resistance in the wires.
How can you increase the magnetic field strength of a solenoid?
Increase current, add more turns, or insert a soft iron core.
Why is there no force when the conductor is parallel to the field?
Because there’s no component of the magnetic field acting across the conductor.
How can the output voltage of a generator be increased?
Rotate faster, use stronger magnets, or add more coil turns.
How does Lenz’s law demonstrate conservation of energy?
The induced current opposes motion, preventing free energy creation.
Describe how a transformer works.
An alternating current in the primary coil produces a changing magnetic field, inducing an emf in the secondary coil through mutual induction.