WorksheetsElectrical Transformers
Total questions: 43
Worksheet time: 24mins
The transformer is a device used to .......... the value of a voltage.
steady
resist
change
anchor
If a transformer reduces voltage, it is called a....................... transformer.
step left
step right
step up
step down
A laminated transformer core reduces the amount of energy that is wasted in the form of........
solidifying
flux
heat
Why transformers work with A.C. current but not D.C.
A.C current produces changing magnetic field.
D.C current produces changing magnetic field.
D.C current is weak
A.C current is powerful
Which of the following does not change in a transformer?
Voltage
Current
Power
Frequency
This picture is an example of a ________________.
Motor
Generator
Step-up transformer
Step-down transformer
Ratio of voltages is equal to ratio of _______________________.
number of iron sheets in core
number of coil
number of turns in coil
number of electromagnetic
A transformer has 100 turns in the primary coil and 25 turns in the secondary coil. When a 120 V is applied to the primary coil, what is the voltage in the secondary coil?
480V
30V
20V
450V
The function of a transformer is to ...
raise and lower the apparent power levels
transfer DC voltage from the primary winding to the secondary winding
increase or decrease A.C voltage or A.C current (Amps) levels
transform mechanical energy into electrical energy
The magnetic material for the core needs to be made of soft iron where its permeability is high
to reduce eddy current loss
to reduce hysteresis loss (loss of energy in the form of heat)
to avoid fringing in the core
to reduce copper loss in the winding
Transformer works on which of the following principle
Lenz’s Law
Ampere's Law
Faraday's Law of Electromagenetic Induction
Fleming's Law
What is the meaning of transformer?
Optimus Prime
A device that transfers electrical energy from one circuit to another
Autobots
Megatron
What is the material used for construction of transformer core?
Aluminium
Copper
Iron
Wood
Calculate potential difference in the secondary coil based on the information given below.
Vp = 240 V
Np = 20
Ns = 125
Vs ?
1500
500
1000
2000
The winding of wire around a core which is connected to a source of alternating current (AC) energy is called the ....... coil.
primary
secondary
tertiary
If a transformer increases voltage, it is called a ......... transformer.
step right
step left
step up
step down
If a transformer reduces voltage, it is called a....................... transformer.
step left
step right
step up
step down
What is transformer?
A device that control the incoming surge to the circuit
A device that transfer direct electrical energy from one circuit to another
A device that transfer alternating electrical energy from one circuit to another
There are two sides of transformer namely _____________ and ____________
(a)
A transformer having turns ratio of 300 : 2400. What type of transformer is this?
Step down transformer
Ideal transformer
Step up transformer
Can transformer works in DC circuit?
Yes
No
Why does transformer cannot be operated under DC condition?
DC current has less harmonics and frequency independent
No current can be transmitted
No changing flux, no induced voltage in the secondary
Mutual inductance is
interactions of one coils magnetic field on other coil as it induces a voltage in the adjacent coil
Interactions of one coils magnetic field on other coil as it induces a current in the adjacent coil.
Interactions of one coils magnetic field on other coil as it induces electrical energy in the adjacent coil
Induced voltage in primary and secondary winding depends on the following except for
Resistor, R
number of turns, N
magnetic flux
Frequency
Why does transformer core is laminated ?
Reduce the effect of eddy current
Minimize losses
Heat dissipation
To make it lighter and portable
A transformer is a device that changes the voltage of
a direct current
an alternating current
Two types of transformer are in terms of voltage
step-in transformer
step-out transformer
step-down transformer
step-up transformer
Calculate voltage in the secondary coil based on the information given below.
Vp = 240 V
Np = 20
Ns = 125
Vs ?
1500 Turns
1500 V
1500A
Transformer is always connected to ___________ supply.
A.C.
D.C.
Transformer transforms _________ from primary to secondary.
Only Current
Only Voltage
Both Voltage and Current
The core of a transformer is made up of:
iron
steel
copper
Electrical symbol of a TRANSFORMER
The following parts of the transformer are...
Emitter/base/ collector
Core/primary coil/secondary coil
Anode/Cathode
The main use of current transformer AKA CT's is...
As measurement transformer
As Current controller
As Voltage regulator
In a 12 V transformer connected to a regular 120 V /5 A line. the output current will be
50 A
20 A
1.2 A
In a transformer with 200 turns in the primary coil and 25 turns in the secondary coil the ratio will be...
1:8
8:1
12:1
The transformer with 3 levels of output voltage two equals and one that is the double is also called...
Center tap transformer
Double tap transformer
Single tap transformer
In analog circuit step down transformers are mostly used in
AC/DC power supplies
Amplifiers
Oscillators
The highest voltage found in a flyback transfomer is..
10 KV
13 Kv
240 V
Is the metal used to build the coils of transformers
Aluminum
copper
steel
The highest output voltage of a center tap transfomer with 10 V in one section is.
20 V
10 V
24 V
How do I know what amp my transformer is?
You have to measure voltage while you are measuring current to get power rating. The transformer will not be giving out the same voltage when shorted out thru a shunt resistor in a multimeter. Take another multimeter, set it up as voltmeter and measure the voltage while measuring current.
(a)
What is volt amps of a transformer?
Transformers are rated in volt amps (VA). It defines the limit of the magnetizing field inside the transformer. If this limit is exceeded, the transformer goes into saturation and ceases to function properly. This is especially important when the transformer has more than one secondary winding.
(a)
