6c-Electromagnetism Flashcards
Q: What happens when an electric current flows through a conductor?
A: A magnetic field is produced around the conductor.
Q: What does the magnetic field around a straight wire look like?
A:
The field forms concentric circles around the wire.
The right-hand rule determines the field direction:
Thumb points in the direction of the current.
Fingers curl in the direction of the magnetic field.
Q: How does a solenoid enhance the magnetic field?A:
A solenoid (coil of wire) creates a strong, uniform magnetic field similar to a bar magnet.
The field strength increases by:
-Increasing the current.
-Increasing the number of coils.
-Using a soft iron core inside the solenoid.
Q: Why does a current-carrying wire experience a force in a magnetic field?
A: The magnetic field of the current interacts with the external magnetic field, producing a force.
Q: What factors affect the size of the force?
A:
Magnitude of the current (higher current = stronger force).
Strength of the magnetic field (stronger field = stronger force).
Angle between the current and field (maximum force when perpendicular, no force when parallel).
Q: How is this principle used in d.c. electric motors
Electric Motors:
A coil of wire in a magnetic field experiences forces on opposite sides.
This creates rotation, which powers the motor.
The split-ring commutator reverses current direction, ensuring continuous rotation.
How is this principle used in d.c Loudspeaker
Loudspeakers:
A coil of wire inside a magnetic field moves back and forth due to changing current.
This vibrates the speaker cone, producing sound waves.
Q: How can you determine the direction of force on a current-carrying wire?
A: Fleming’s Left-Hand Rule:
Thumb → Force (Motion)
First Finger → Magnetic Field (North to South)
Second Finger → Current (Positive to Negative)
Q: How does the force change with field and current direction?
A:
Reversing the current or magnetic field reverses the force direction.
Increasing the current or field strength increases the force.
Practical: Investigating the Motor Effect
Observing Force on a Wire
Method: Place a wire in a magnetic field and pass a current through it.
Observation: The wire moves due to the motor effect.
Conclusion: Confirms Fleming’s Left-Hand Rule.
Practical: Investigating the Motor Effect
Building a Simple Electric Motor
Method: Use a coil, magnets, and a power source to create rotation.
Observation: The coil spins due to the force acting on the current-carrying wire.
Conclusion: Demonstrates how motors convert electrical energy into mechanical motion.
