Magnetic Effect on current-carrying conductor
How does reversing current affect solenoid polarity?
It swaps north and south poles.
What interaction produces the motor effect?
The magnetic field of the wire interacts with the external field.
What energy transfer involved in DC motor?
Electrical energy → mechanical/kinetic energy
What causes induction?
Change in magnetic flux through a conductor.
Why do transformers only work with AC?
AC creates changing flux; DC doesn’t.
Describe how to find a solenoid’s poles using current direction.
Right hand grip rule OR clock face rule
State Fleming's Left-Hand Rule & it's application.
Thumb = force, First = field, Second = current; shows force direction.
How can motor speed be increased?
Stronger field, higher current, or more coil turns.
How can induced emf be increased?
Faster motion, more turns, stronger magnet.
What is the purpose of soft iron cores?
Efficient magnetic coupling; easy magnetization/demagnetization.
Why does a solenoid act like a bar magnet?
Its field lines form a similar uniform pattern.
Why is there no force when wire is parallel to field?
Current and field are parallel → no perpendicular component.
Why is split ring commutator needed in a DC motor?
To reverse current each half-turn, maintaining coil rotation direction.
State Lenz’s Law in terms of energy.
Induced current opposes change, conserving energy.
Explain how step-up transformers reduce power loss.
Increase voltage → lower current → less heating (I²R).
Explain how a soft iron core strengthens a solenoid.
It becomes magnetized, increasing field density.
What happens when either current or field strength doubles?
Force doubles (directly proportional).
How is emf induced in a generator?
Coil cuts magnetic field lines when rotated.
Why does a magnet fall slower through a copper tube?
Induced currents oppose motion (Lenz’s Law).
What type of energy conversion occurs in transformers?
Electrical → magnetic → electrical.
Why does a current-carrying wire create a magnetic field?
Moving charges experince force and produce magnetic fields.
Explain why reversing current reverses force.
Reversal changes current direction → opposite magnetic interaction.
Explain why AC generators produce alternating current.
Coil rotation reverses direction of cutting field lines every half turn.
Arrange the sequence of how AC is produced using electromagnetic induction.
1 Alternating flux
2 Alternating current induced
3 Rotating coil in field
4 Alternating emf / current
Rotating coil in field → alternating flux → alternating current induced → alternating emf/current
Why is power transmission done at very high voltages able to save cost?
Minimizes energy loss by reducing current in cables, able to use thinner cable, thus cutting cost.