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WorksheetsM3.15 Cat B Transformers
Total questions: 23
Worksheet time: 15mins
Primary winding of a transformer is determined by _________.
which winding has more turns
which winding is nearer to the load
which winding is connected to the source
which side has the highest voltage
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 levels
transform mechanical energy into electrical energy
Insulators are put between core lamination ...
to prevent flux leaks to the neighboring steel sheet
to reduce the cross-sectional area of the core
to reduce eddy currents
to prevent rusting in the lamination
The electrical energy is transferred through the ... in a transformer.
electric field
rotor
air space
magnetic field
The winding wire is coated with varnish so that ...
it can reduce the heat in the transformer
it can reduce the hysteresis loss
it can prevent the wire from rusted
each turn of the winding is insulated from every other turn
Choose the correct statement:
The efficiency of a transformer is the percentage of the ratio of its input power to the output power
The ratio of the input apparent power to the output apparent power is less than 1 for a practical transformer
The ratio of the number of turns in the secondary winding to the number of turn in the primary winding determine the type of the transformer
Copper loss is due to eddy current in the core
A step up transformer _____________.
decreases voltage
decreases current
increases power
increases frequency
Transformer is able to transform both AC and DC Voltages in a Circuit
True
False
The input voltage to a transformer is usually ____ voltage.
AC
DC
both AC & DC
What type of device can increase and decrease voltage?
Generators
Transformers
Galvanometers
Electric motors
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
Electrical symbol of a TRANSFORMER
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
Is the metal used to build the coils of transformers
Aluminum
copper
steel
HOW MANY WINDINGS ARE THERE IN AUTOTRANSFORMER?
TWO
ONE
THREE
AUTO TRANSFORMER WORKS ON -----------INDUCTION.
SELF
MUTUAL
NONE
THE RATIO OF OUTPUT POWER TO INPUT POWER IS KNOWN AS --------------------
LOSS
EFFICIENCY
GAIN
