Fundamentals of Magentism Flashcards
Magnetic flux lines:
a) are visible in air
b) are visible in water
c) do not exist
d) cannot be insulated
d) cannot be insulated
Like magentic poles:
a) attract
b) repel
c) cancel the effects of one another
d) neither attract nor repel
b) repel
A material is permeable if:
a) flux lines are repelled by it
b) magnetic fields are equal within it
c) magnetic fields are negative in it
d) flux lines concentrate in it
d) flux lines concentrate in it
The material with highest reluctance is:
a) aluminum
b) iron
c) nickel
d) cobalt
a) aluminum
Magnetic flux lines:
a) move from north to south outside a magnet
b) move from south to north outside a magnet
c) follow the path of least inductance
d) follow the path of most inductance
a) move from north to south outside a magnet
A permanent magnet loses magnetic strength when someone:
a) hammers on it
b) heats it
c) exposes it to an alternating magnetic field
d) does any of the above
d) does any of the above
The strength of an electromagnet is determined by:
a) the number of turns of wire and the amount of current flowing through it
b) the tensile strength of the wire used to wind the coil
c) how much weight can be supported on the electromagnet
d) the amount of time the electromagnet takes to reach saturation
a) the number of turns of wire and the current flowing through it
A device that pulls a piece of iron to its centre is called:
a) permeable
b) reluctant
c) an electromagnet
d) a solenoid
d) a solenoid
The right hand rule for conductors:
a) must be used with the conventional theory of current direction
b) determines the number of flux lines around a wire
c) determines the north or south pole of the conductor
d) can only be used south of the equator
a) must be used with the conventional theory of current direction
When using the right-hand rule for coils:
a) the thumb points to the north pole
b) the fingers point to the north pole
c) the thumb points in the direction of the flux lines
d) the fingers point in the direction of the flux lines
a) the thumb points to the north pole
An electric motor changes electrical energy to mechanical energy:
a) since flux lines in the same direction attract
b) since flux lines in the same direction repel
c) because an electromagnet attracts iron
d) since like magnetic poles attract
b) since flux lines in the same direction repel
Voltage is generated in a conductor when:
a) a magnetic field is present in the conductor
b) a magnetic field moves at an angle through a conductor
c) magnetic fields move in parallel with a conductor
d) the magnetic field is stationary in a conductor
b) a magnetic field moves at an angle through a conductor
The amount of voltage produced in a conductor is determined by:
a) how quickly the flux lines move across the conductor
b) the strength of the magnetic field
c) both a and b
d) neither a nor b
c) both a and b
When current flowing in a coil of wire is stopped:
a) a self-induced voltage occurs
b) the magnetic field rises
c) magnetic flux lines reverse direction
d) magnetic flux line move from south to north
a) a self-induced voltage occurs
Mutual induction occurs:
a) within a single coil
b) between two coils or conductors
c) among three coils
d) only when the magnetic field collapses
b) between two coils or conductors
