Physics P4

Created by

Lily

Cards (40)

What are the two poles of a magnet called?
North and South
What happens when two like poles of magnets are brought together?
They repel each other
What occurs when two opposite poles of magnets are brought together?
They attract each other
What are permanent magnets?
Magnets that are always magnetic and always have poles
How can induced magnets be created?
By stroking magnetic materials with a permanent magnet
What materials are commonly used to create induced magnets?
Iron, Nickel, and Cobalt
How are magnetic fields represented?
Using field lines that point from north to south
What happens to the strength of a magnetic field as the distance from the magnet increases?
The strength of the field decreases
What does a small plotting compass do in relation to magnetic fields?
It shows the direction of the magnetic field at a certain point
What is the Earth's core described as?
Magnetic
Why does a freely suspended magnetic compass point North?
Because it aligns itself with the Earth's magnetic field lines
Where is the magnetic north pole located?
Over North Canada
Why is the Earth's magnetic pole above Canada considered a magnetic South Pole?
Because like poles repel each other
What does current flowing in a wire produce?
A magnetic field around the wire
What rule dictates the direction of the magnetic field around a wire?
The right hand grip rule
How does the strength of the magnetic field change with the current flowing?
The greater the current, the stronger the magnetic field
What happens to the magnetic field as the distance from the wire increases?
The magnetic field becomes weaker
What is a solenoid?
A coil of wire with current flowing through it
How does coiling the wire in a solenoid affect the magnetic field?
It enhances the magnetic effect by aligning the field
What increases the strength of a solenoid's magnetic field?
Inserting an iron core in the center
What factors can affect the strength of the magnetic field produced by a solenoid?
Size of current
Length of coil
Cross-sectional area
Number of turns (coils)
Type of core used
What type of force do two magnets exert on each other?
A magnetic force of attraction or repulsion
How does the magnetic field around a wire differ from the magnetic field between two magnets?
The magnetic field around a wire is circular, while between magnets it is straight
What does Fleming's Left-Hand Rule help determine?
The direction of the force on a current-carrying conductor in a magnetic field
What is the formula for calculating force in a magnetic field?
F = BIL
What does magnetic flux density measure?
The number of flux lines per meter squared
How does an electric motor operate?
It rotates a coil of current-carrying wire between fixed permanent magnets
What happens to electrons in a conductor when the magnetic field changes?
They move to one side, creating a potential difference
What is generated when a wire cuts through a magnetic field?
A potential difference
What type of current flows when a coil of wire is connected to a complete circuit after being rotated in a magnetic field?
An alternating current
What happens to the magnetic field when alternating current is used?
The magnetic field constantly changes direction
How does a transformer work with alternating current?
The changing magnetic field induces a current in the secondary coil
What happens if the primary current in a transformer is direct?
Nothing would be induced in the secondary coil
What is a step-up transformer?
A transformer with more turns on the secondary coil
What is a step-down transformer?
A transformer with fewer turns on the secondary coil
What is the relationship between the number of coils and the potential difference in a transformer?
Number of coils on primary / number of coils on secondary = pd of primary / pd of secondary
What do dynamic microphones produce?
A current proportional to the sound signal
How does a dynamic microphone work?
Sound waves cause a coil to move within a magnetic field, inducing a current
What happens to the current in a loudspeaker?
The current flows into the coil, causing it to move and produce sound waves
What are the steps involved in how dynamic microphones work?
Sound waves cause pressure variations.
Coil moves within a magnetic field.
Current is induced in the coil.
Current flows to a loudspeaker.
Loudspeaker converts current back to sound waves.