WorksheetsAC Generators
Total questions: 21
Worksheet time: 12mins
Which ONE of the following actions will NOT cause an increase in the induced emf in a coil if the coil is rotated in a uniform magnetic field?
Rotating the coil faster
Increasing the strength of the magnetic field
Increasing the number of turns of the coil
Replacing the coil with a coil of lower resistance
Some learners decided to build a small electrical generator in the laboratory. They then used this generator to investigate how the magnitude of the induced emf would change as the magnetic field strength changed.
Which ONE of the following is CORRECT regarding the variables for the investigation?
DEPENDENT VARIABLE: Magnitude of induced emf
INDEPENDENT VARIABLE: Number of turns of coil of generator
CONTROL VARIABLE: Magnetic field strength
DEPENDENT VARIABLE: Number of turns of coil of generator
INDEPENDENT VARIABLE: Magnitude of induced emf
CONTROL VARIABLE: Magnetic field strength
DEPENDENT VARIABLE: Magnitude of induced emf
INDEPENDENT VARIABLE: Magnetic field strength
CONTROL VARIABLE: Number of turns of coil of generator
DEPENDENT VARIABLE: Magnetic field strength
INDEPENDENT VARIABLE: Number of turns of coil of generator
CONTROL VARIABLE: Magnitude of induced emf
Which ONE of the following changes may lead to an increase in the emf of an AC generator without changing its frequency?
Decrease the resistance of the coil.
Increase the area of the coil.
Increase the resistance of the coil.
Decrease the speed of rotation.
The speed of rotation of the coils in an AC generator is increased. Which ONE of the following combinations of frequency and output voltage for the generator will occur as a result of the change?
FREQUENCY: Increases
OUTPUT VOLTAGE: Increases
FREQUENCY: No change
OUTPUT VOLTAGE: Increase
FREQUENCY: Decrease
OUTPUT VOLTAGE: Decrease
FREQUENCY: Increase
OUTPUT VOLTAGE: No change
Graph P represents the output emf of an AC generator. Graph Q is the output emf after a change has been made using the same generator. Which one of the following changes has been made to the generator to produce graph Q?
The number of turns of the coil has been doubled
The surface area of the coil has been doubled
The speed of rotation has been doubled
The strength of the magnetic field has been doubled
The voltage induced in a conductor is ___________ ___________ to the rate which the conductor cuts the magnetic lines of force.
inversely proportional
directly proportional
negatively coorelated
absolutely opposite
In order for electromagnetic induction to occur, you need...
a conductor
a magnetic field
relative motion
all three
What is another name for electromagnetic induction?
The motor effect
The generator effect
A solenoid
A flux capacitor
How is contact between the coil and circuit maintained in an AC generator?
A split ring commutator connects to each side for half a turn
It cannot be maintained.
The alternator can only complete one revolution and must then be rotated in reverse
Slip rings and brushes allow continuous connection
What is the voltage from an AC generator half a turn after maximum positive output?
Half the maximum output
Maximum positive output again
Zero voltage
Maximum negative output
The graph shows the output of an a.c. generator. The coil in the generator rotates 20 times in one second.
Which graph shows the output when the coil rotates 10 times in one second?
A coil is rotated steadily between the poles of a magnet. The coil is connected to an oscilloscope.
Which graph shows the output voltage V against time t?
Which diagram represents the voltage output of a simple a.c. generator?
The diagram shows an a.c. generator.
With the coil in the position shown, the output voltage is +10 V. When does the output voltage become –10 V?
when the coil has turned 90°
when the coil has turned 180°
when the coil has turned 270°
when the coil has turned 360°
Dynamos are generators that produce direct current.
True
False
Dynamos contain...
slip rings
a split-ring commutator
Select the correct voltage graph for a dynamo.
