Magnetic Effect of a Current and the d.c. Motor
88 questions· page 1 of 9
A beam of beta particles travelling vertically downwards enters the magnetic field between two magnetic poles.
The beta particles experience a force due to the magnetic field.
What is the direction of the force on a beta particle as it enters the magnetic field?
Options
A towards the top of the page
B towards the bottom of the page
C into the page
D out of the page
Students are asked to suggest factors that affect the speed of rotation of a direct current (d.c.) motor.
Three of their suggestions are listed.
- the strength of the magnetic field
- the current
- the number of turns on the coil
Which suggestions are correct?
Options
A 1, 2 and 3
B 1 and 2 only
C 1 and 3 only
D 2 and 3 only
Two current-carrying conductors are placed next to each other. The current in the conductors is in the same direction.
Which statement about the forces experienced by the conductors is correct?
Options
A The forces are in the same direction, and the conductors are forced apart.
B The forces are in opposite directions, and the conductors are forced apart.
C The forces are in the same direction, and the conductors are forced towards each other.
D The forces are in opposite directions, and the conductors are forced towards each other.
Which component is not needed to make a simple d.c. motor work?
Options
A battery
B brushes
C diode
D split-ring commutator
The diagram shows a loudspeaker that is producing a sound.
A student writes four sentences about the loudspeaker.
- There is a direct current in the coil of wire.
- The current in the coil produces a changing magnetic field.
- A force is produced on the coil of wire attached to the cone.
- The cone spins around due to the force.
Which sentences are correct?
Options
A 1 and 2
B 1 and 4
C 2 and 3
D 3 and 4
The diagram shows a wire carrying a current in a magnetic field.
What is the direction of the force on the wire?
Options
A left to right
B right to left
C into the page
D out of the page
The diagram shows a simple d.c. motor.
What is the part labelled Q?
Options
A a coil
B a magnet
C a slip ring
D a split-ring commutator
Students are asked to draw the pattern and direction of the magnetic field due to a direct current (d.c.) in a straight wire.
Diagrams 1, 2 and 3 are three of their answers.
The students do not know the direction of the current in the wire.
Which diagrams show possible patterns and directions for the magnetic field due to the current in the wire?
Options
A 1, 2 and 3
B 1 and 3 only
C 1 only
D 2 only
A straight vertical wire carries a current in the direction shown.
What is the pattern of the magnetic field around the wire seen by an observer viewing the wire from the position shown?
Options
Which part of a simple d.c. motor reverses the direction of current in the coil once every half rotation of the coil?
Options
A the armature
B the brushes
C the slip rings
D the split-ring commutator