21 Questions
What produces a current in dynamic microphones?
Pressure variations in sound waves
In dynamic microphones, what causes the coil to move and induce current?
Pressure variations in sound waves
Which principle is involved in the operation of dynamic microphones?
Fleming's Left Hand Rule
What interacts to cause the movement of the cone in loudspeakers?
Magnetic field from the magnet and current
What is responsible for producing pressure variations in loudspeakers?
Movement of the cone
What happens if the magnetic field changes while a current flows in a conductor?
The current will produce its own magnetic field that opposes the change inducing it
How is direct current (DC) produced in an electric generator like a dynamo?
By connecting the ends of the coil of wire to a split ring commutator
In an alternator, what type of current is produced when the coil of wire rotates between two permanent magnets?
Alternating current (AC)
What results from more coils on the secondary coil of a transformer?
Step up transformer with increased voltage
What happens if the primary current in a transformer is direct current (DC)?
It produces a constant magnetic field and fails to induce a current in the secondary coil
What principle states that when a wire cuts through a magnetic field, it induces an electromotive force (emf) or voltage?
Faraday's Law of Electromagnetic Induction
What dictates the direction of the magnetic field produced by a current-carrying wire?
The Right Hand Grip Rule
In a solenoid, why does having an iron core in the center increase the strength of the magnetic field?
It makes it easier for magnetic field lines to pass through than air
What rule is used to determine the direction of force felt when a wire carrying current interacts with a magnetic field?
Fleming's Left Hand Rule
What is the relationship between magnetic flux density and the force acting on a current-carrying wire in a magnetic field?
Direct relationship
How does an electric motor generate motion?
By using permanent magnets and a coil of current-carrying wire
What phenomenon results in a potential difference being induced across a conductor?
Electromagnetic Induction
When there is relative movement between a conductor and a magnetic field, what is induced across the conductor?
Potential difference
What happens to the force exerted on a wire when its direction is perpendicular to the magnetic field lines?
It decreases
What determines the strength of a magnetic field around a wire?
The cross-sectional area of the wire
What shape does the magnetic field in a solenoid resemble?
Helix or spiral
Test your knowledge on magnetism, currents, and the relationship between them. Learn about the right hand grip rule, the effects of current strength and distance on magnetic fields, and the magnetic field shape created by a solenoid.
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