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WorksheetsDC motor concepts
Total questions: 30
Worksheet time: 47mins
What must be complete for a circuit to work?
The wires must be colored
A light bulb must be present
A battery must be fully charged
The path must be complete
What happens when the poles of two magnets are brought close to each other?
Nothing happens
They always repel
They merge into a single magnet
Opposite poles attract and the same poles repel
What is an electromagnet?
A natural magnet found in the earth
A magnet that can be turned on or off
A magnet that can only attract metals
A type of permanent magnet
What causes the poles on an electromagnet to switch places?
Moving the magnet closer to metal objects
Heating the electromagnet
Flipping the battery
Shaking the electromagnet
What is the purpose of a commutator in an electric motor?
To cool down the motor
To automatically switch the direction of current
To increase the motor's power
To reduce the motor's speed
What is the stator in an electric motor?
The part that spins
The switch that controls the motor
The part that doesn't move
The battery that powers the motor
What is the rotor in an electric motor?
The outer casing of the motor
The wires inside the motor
The battery connection
The part that spins
How can the torque of an electric motor be increased?
By using a lighter armature
By adding more loops to the armature
By using a smaller battery
By using fewer wires
What is the role of brushes in an electric motor?
To clean the commutator
To maintain electrical contact with the commutator
To lubricate the motor
To cool down the motor
What type of motor was primarily discussed in the video?
Servo motor
AC motor
Stepper motor
DC motor
What happens when you flip the battery in a circuit?
The current flows the other way
The device connected to the circuit turns off
The current stops flowing
The circuit breaks
What is the effect of wrapping more wires around the armature loops?
Has no effect on the motor
Decreases the motor's efficiency
Makes the electromagnets stronger
Makes the electromagnets weaker
What is the function of the armature in an electric motor?
To spin and create motion
To act as a permanent magnet
To supply power to the motor
To hold the motor together
How does reversing the polarity of an electromagnet affect it?
It loses its magnetic properties
It becomes a permanent magnet
North becomes south and vice versa
It stops being a magnet
What is the significance of the commutator's design in an electric motor?
It makes the motor more energy-efficient
It prevents the motor from overheating
It switches the direction of current automatically
It allows the motor to spin in one direction only
Motors convert ________ energy into _______ energy.
Electrical, mechanical
Mechanical, electrical
Voltage, electrical
As you increase the load on the motor, it has to draw more ________ from the battery.
Voltage
Brush load
Current
As you increase torque, what is also increased?
Current
Voltage
Resistance
DC motors are found in:
Automobiles
Industrial Equipment
VEX Robotics
Cats
What is the rotating part of the electric motor?
Brush
Armature
Battery
When the electric current in wire XY is in the direction shown, there is an upward force on the wire.
If the north and south poles of the magnet exchange positions, in which direction will the force on the wire act?
downwards
upwards
to the left
to the right
A student carries out an experiment to see the effect of a magnetic field on a wire carrying a current. The wire moves upwards as shown.
What should the student do to make the wire move downwards?
change the direction of the current
move the poles of the magnet closer together
send a smaller current through the wire
use a stronger magnet
A current-carrying coil in a magnetic field experiences a turning effect.
How can the turning effect be increased?
increase the number of turns on the coil
reduce the size of the current
reverse the direction of the magnetic field
use thinner wire for the coil
The diagram shows a simple DC electric motor which is rotating.
Which change will make the motor rotate more quickly?
reversing the polarity of the magnets
reversing the battery
removing the magnets
using more powerful magnets
A simple DC electric motor is fitted with a coil that rotates in a magnetic field. A commutator connects the power supply to the coil.
What is the purpose of the commutator?
It converts AC into DC in the coil.
It prevents the current from becoming too great, because the coil has a low resistance
It reverses the direction of the current in the coil after every 180° rotation of the coil
It switches the current off momentarily after every 90° rotation of the coil
A coil carries a current in a magnetic field. The coil experiences a turning effect.
Which device uses this effect?
a DC motor
an electromagnet
a relay
a transformer
A wire XY lies between the poles of a magnet. The diagram shows the upward force on the wire XY caused when there is an electric current in the direction XY as shown.
Three tests are made using this apparatus:
1 The current direction is reversed.
2 The N and S poles are swapped around.
3 The current is switched off.
Which will result in no change in the size of the force on the wire?
1 and 2 only
1 only
2 only
3 only
The diagram shows a current-carrying wire placed between two magnetic poles. The current is in the direction shown.
What is the direction of the force on the wire?
towards the bottom of the page
towards the top of the page
towards the left-hand side of the page
towards the right-hand side of the page
A current-carrying wire lies between the poles of two magnets, as shown.
What is the direction of the force on the wire?
into the plane of the paper
out of the plane of the paper
towards the left
towards the right
What does not alter the size of the turning effect on the coil of an electric motor?
the strength of the magnetic field
the direction of the current in the coil
the number of turns in the coil
the size of the current in the coil
