Magnetic Fields Flashcards
What is a magnetic field?
A field surrounding a permanent magnet or a current-carrying conductor in which magnetic objects experience a force
How can you detect the presence of a magnetic field?
With a small plotting compass - the needle will deflect in the presence of a magnetic field
What do we use magnetic field lines for?
Mapping magnetic field patterns around magnets and current-carrying conductors
What are magnetic field patterns?
Useful visual representations that help us to interpret the direction and the strength of the magnetic fields
What is the arrow on a magnetic field line?
The direction in which a free north pole would move
What way does the arrow on a magnetic field line point?
North to south
What do equally spaced and parallel magnetic field lines represent?
A unform field
What is a uniform magnetic field?
One in which the strength of the magnetic field does not vary
When is a magnetic field stronger?
When the magnetic field lines are closer
Where is the magnetic field strongest for a bar magnet?
At the north and south poles
How can iron filings be used to reveal the magnetic field around a bar magnet?
Place a piece of paper on top of a bar magnet, and sprinkle iron filings around the piece of paper. The magnetic field induces magnetism in the filings, which line up in the magnetic field
What happens when a wire carries a current?
A magnetic field is created around the wire
What is the magnetic field around a current-carrying wire created by?
The electrons moving within the wire
What does any charged particle that moves create?
A magnetic field in the space around it
What are the magnetic field lines for a current-carrying wire?
Concentric circles centered on the wire and perpendicular to it
How can the direction of the magnetic field for a current-carrying wire be determined?
Using the right hand grip rule
How can the direction of the magnetic field for a current-carrying wire be determined?
Using the right-hand grip rule
How does the right-hand grip rule indicate the direction of the magnetic field for a current-carrying wire?
The thumb points in the direction of the conventional current, and the direction of the field is given by the direction in which the fingers curl around the wire
What do both a single coil and solenoid produce?
Noth and south poles at their opposite faces
What is the magnetic field pattern outside a solenoid similar to?
That for a bar magnet
What is the magnetic field at the center of the core of a solenoid?
Unform - parallel and equidistant magnetic field lines
What happens when a current-carrying conductor is placed in an external magnetic field?
The two fields interact just like the fields of two permanent magnets
What type of force do the two magnets experience when a current-carrying conductor is placed in an external magnetic field?
Equal and opposite forces
How can the direction of the force experienced by a current-carrying conductor placed perpendicular to an external magnetic field be determined?
Using fleming’s left-hand rule