WorksheetsGr 9_Asg Generator & Transformer
Total questions: 25
Worksheet time: 30mins
A step-down transformer is 100% efficient. It has an input voltage of 240 V a.c. and an output voltage of 60 V a.c.
The current in the primary coil is 0.50 A.
What is the current in the secondary coil?
0.13 A
0.50 A
2.0 A
8.0 A
The diagram shows a transformer. What is the output voltage?
0.35 V
2.9 V
4600 V
105 000 V
In an a.c. generator, a coil is rotated in a magnetic field and an electromotive force (e.m.f.) is induced in the coil. In which position of the coil does the e.m.f. have the largest value?
A transformer has Np turns in the primary coil and Ns turns in the secondary coil.
Which row gives the values of Np and Ns for a transformer that steps up a voltage of 1200 V to 36 000 V?
Np = 2000
Ns = 60 000
Np = 2000
Ns = 600 000
Np = 60 000
Ns = 2000
Np = 600 000
Ns = 2000
The diagram shows a transformer.
The input voltage is 240 V. What is the output voltage?
6.0 V
12 V
20 V
40 V
Transformers are used in the transmission of electrical power to houses. Which type of transformer is used at the power station prior to connection to the power lines and which type is used prior to delivery to the houses?
Power station: Step Down
Before Houses: Step Down
Power station: Step Down
Before Houses: Step Up
Power station: Step Up
Before Houses: Step Down
Power station: Step Up
Before Houses: Step Up
The diagram shows an a.c. generator rotating in a clockwise direction.
What are the names of parts 1 and 2?
1: Brush
2: Slip Ring
1: Brush
2: Slip Ring Commutator
1: Slip Ring
2: Slip Brush
1: Slip Ring
2: Slip Ring Commutator
The diagram shows a wire between two magnets. An electromotive force (e.m.f.) is induced in the wire when it is moved up between the two magnets.
Four tests are done.
1 The direction of movement of the wire is reversed.
2 The direction of the magnetic field is reversed.
3 The wire is moved more quickly.
4 The magnetic field strength is decreased.
Which tests will induce a smaller e.m.f. in the wire?
1 and 2
1 and 3
3 and 4
4 only
The diagram shows an a.c. generator used to power a lamp. The coil rotates in a clockwise direction.
Which magnetic poles are X and Y?
X: N Pole
Y: N Pole
X: N Pole
Y: S Pole
X: S Pole
Y: N Pole
X: S Pole
Y: S Pole
A transformer is needed to convert a supply of 240 V a.c. into 4800 V a.c.
Which pair of coils would be suitable for this transformer?
number of turns
on primary coil NP= 50
number of turns
on secondary coil NS= 1000
number of turns
on primary coil NP= 240
number of turns
on secondary coil NS= 48 000
number of turns
on primary coil NP= 480
number of turns
on secondary coil NS= 24
number of turns
on primary coil NP= 2000
number of turns
on secondary coil NS= 100
A step-down transformer is 100% efficient. It has an input voltage of 240 V a.c. and an output voltage of 60 V a.c. The current in the primary coil is 0.50 A.
What is the current in the secondary coil?
0.13 A
0.50 A
2.0 A
8.0 A
The diagram shows a coil of wire between the poles of a magnet.
The coil consists of 20 turns of insulated wire.
The coil is connected to a variable resistor and a power supply.
How can the turning effect on the coil be increased?
by moving the poles of the magnet closer to the coil
by reducing the number of turns on the coil while keeping the current constant
by increasing the resistance of the variable resistor
by reversing the terminals of the power supply
A 100% efficient transformer has 6000 turns on its primary coil and 600 turns on its secondary coil. The output voltage of the transformer is 12 V. A resistor is connected across the secondary coil and dissipates 24 W of power.
What is the current in the primary coil of the transformer?
0.050 A
0.20 A
5.0 A
20 A
The diagram shows an electric generator with the coil in a vertical position.
Which row describes the generator?
the generator produces = AC
the voltage output
will be zero when = the coil is horizontal
the generator produces = AC
the voltage output
will be zero when = the coil is vertical
the generator produces = DC
the voltage output
will be zero when = the coil is horizontal
the generator produces = DC
the voltage output
will be zero when = the coil is vertical
The diagram shows a transformer. There are 460 turns on the primary coil and 24 turns on the secondary coil. The primary voltage is 230 V. What is the secondary voltage?
2.0 V
12 V
48 V
4400 V
A 100% efficient transformer converts a 240 V input voltage to a 12 V output voltage. The output power of the transformer can be a maximum of 20 W.
The output is connected to two 0.30 A bulbs in parallel. One of the bulbs fails.
How does the current in the primary coil change?
It decreases by 0.30 A.
It decreases by 0.015 A.
It increases by 0.15 A.
It remains unchanged.
What is the purpose of step up transformers in the national grid?
To decrease the voltage of electricity
To minimize energy losses
To increase the voltage of electricity
To generate electricity
What is the purpose of step down transformers in the national grid?
To decrease the voltage of electricity
To minimize energy losses
To increase the voltage of electricity
To generate electricity
What is the role of a transformer?
To increase the voltage of electricity
To transfer current from the primary coil to the secondary coil
To decrease the voltage of electricity
To generate electricity
What is the purpose of the iron core in a transformer?
To generate electricity
To decrease the voltage of electricity
To increase the voltage of electricity
To connect the primary and secondary coils
What is the main source of energy input for a generator?
Chemical energy
Mechanical energy
Electrical energy
Nuclear energy
In a transformer, if the number of turns in the primary coil is greater than the number of turns in the secondary coil, what happens to the voltage?
Voltage increases
Voltage decreases
Voltage remains the same
Voltage depends on the core material
Which of the following materials is commonly used as the core in a transformer?
Plastic
Copper
Iron
Aluminum
This picture is an example of a ___________
Step-Up Transformer
Motor
Step-Down Transformer
Generator
The function of a transformer is to ...
Raise and lower the apparent power levels
Increase or decrease A.C voltage or A.C current levels
Transfer DC voltage from the primary winding to the secondary winding
Transform mechanical energy into electrical energy
