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WorksheetsF5 Chp 3.2 DC Motor
Total questions: 11
Worksheet time: 11mins
Name
Class
Date
1.
When the coil is part of a d.c. motor, what must be connected directly to X and Y?
a)
d.c. supply
b)
slip rings
c)
soft-iron core
d)
split-ring commutator
2.
The diagram shows three pairs of parallel wires with the currents in the directions shown.
Which forces do the pairs of wires experience?
X, Y, Z
Which forces do the pairs of wires experience?
X, Y, Z
a)
attraction, none, repulsion
b)
attraction, repulsion, attraction
c)
none, attraction, none
d)
repulsion, attraction, repulsion
3.
Each of the diagrams below is a cross-section through two parallel current-carrying conductors.
Which diagram correctly shows the magnetic field pattern formed by the currents in the two conductors?
Which diagram correctly shows the magnetic field pattern formed by the currents in the two conductors?
a)
A
b)
B
c)
C
d)
D
4.
A wire hangs between the poles of a magnet.
When there is a current in the wire, in which direction does the wire move?
When there is a current in the wire, in which direction does the wire move?
a)
A
b)
B
c)
C
d)
D
5.
What is the part of a simple d.c. motor that reverses the direction of current through the coil every half-cycle?
a)
The armature
b)
The brushes
c)
The commutator
d)
The slip rings
6.
The diagram shows a beam of electrons entering a magnetic field.
What is the effect of the magnetic field on the electrons?
What is the effect of the magnetic field on the electrons?
a)
They are deflected into the plane of the diagram.
b)
They are deflected out of the plane of the diagram.
c)
They are deflected towards the bottom of the diagram.
d)
They are deflected towards the top of the diagram.
7.
An alternating current is passed through a wire stretched between the poles of a magnet.
Which way will the wire move?
Which way will the wire move?
a)
left and right
b)
right only
c)
up and down
d)
up only
8.
X and Y are wires carrying electric currents at right angles to the page. P, Q and R are plotting compasses. Any effect of the Earth’s magnetic field has been ignored.
What is true about the direction and size of the currents?
What is true about the direction and size of the currents?
a)
A
b)
B
c)
C
d)
D
9.
The diagram shows a beam of electrons entering a magnetic field. The direction of the field is into the page.
What will be the initial direction of the deflection of the electrons as the beam passes through the field?
What will be the initial direction of the deflection of the electrons as the beam passes through the field?
a)
into the page
b)
out of the page
c)
towards the bottom of the page
d)
towards the top of the page
10.
The diagram shows a two-pole single-coil electric motor.
The split-ring commutator reverses the current in the coil as it rotates.How many times is the current reversed if the coil is rotated once?
The split-ring commutator reverses the current in the coil as it rotates.How many times is the current reversed if the coil is rotated once?
a)
1
b)
2
c)
3
d)
4
11.
Which of the following has no effect on the size of the turning effect on the coil of an electric motor?
a)
the size of the current in the coil
b)
the direction of the current in the coil
c)
the number of turns in the coil
d)
the strength of the magnetic field
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