6.3 Elecromagnetism Flashcards
What is a magnetic field?
The reigion around a permanent magnet or a moving charge in which another body with magnetic properties will feel a force.
Region where a force will act at a distance.
What are magnetic feild lines?
These show the shape of the field and the direction. The direction of the feild line at a point shows the direction in which a compass would point.
What is a solenoid?
A long coil of current carrying wire.
What is a magnetic field caused by?
Either a permanent magnet or by moving charges (an electric current).
What will a magnetic field act on?
A magnetic material or a charged particle.
What are magnetic fields represented by?
Field lines.
What are the shape and direction of magnetic feild lines dependent on?
The nature of the magnetic field .
What is always true about magnetic field lines?
The always point from north to south, and the closer they are drawn, the stronger the field is.
Describe magnetic field lines.
Magnetic field lines have no beginning or end, they always form closed loops. The direction is from a north pole to a south pole, but they do not begin at a orth pole or end at the south pole.
What would the field lines look like on this magnet?
What would the field lines look like on these magnets?
How can you determine the direction of the magnetic field lines when an electric current flows through a straight conductor?
Using the right-hand rule. By aligning the thumb on your right hand parallel to the direction of the conventional current in the wire, the curling of the fingures will indicate the direction of the field lines.
What does the magnetic field lines look like of a straight current- carrying wire shaped into a coil?
Describe what the magnetic field lines would look like after shaping a straight current-carrying wire into a single coil?
On one side of the coil, the magnetic field lines are in a clockwise direction, whereas on the other side they are in an anticlockwise direction. The vector addition of the fiekds around each wire leads to an increase in the strength of the magnetic fields within the coil.
Describe what a solenoid is?
A long wire wrapped around a hollow cylinder and current is passed through.
What does the north-south polarity of a solenoid depend on?
Direction of the current.
How can you work out which side the north pole of a solenoid is?
Using a variation of the right hand rule- if curing your fingers indicates the direction of the current flowaround the solenoid, your thumb will point towards north.
What does the magnetic field associated with a solenoid look like?
Describe the magnetic field inside and outside a solenoid.
Inside the field is strongest and very uniform. Outside, the firls is similar to the magnetic field produced by a bar magnet and that to earths magnetic field.
What happens if a cylinder of iron is placed inside a solenoid?
The magnetic field in increased considerably.
What does the earths magnetic field look like?
The earth’s magnetic field changes direction over a period of many thousands of years, why might this be significant?
The means the earths magnetic North pole will switch to a south pole.
What does Flemming’s left-hand rule show?
Shows the direction of the force on a conductor carrying a current in a magnetic field.
What does each fingre represent in Flemming’s left-hand rule?
Thumb- Force
First fingre- Feild
Second fingre- Current