Electronics Principles and
Applications Chapter 4
What does the power supply do? ANS:It changes the ac to a form compatible with the circuit such as dc.
What is a bipolar power supply? ANS:A power supply that supplies both positive and negative voltages
What does it mean if a power supply has a wide voltage tolerance? ANS:It means that its voltage may
vary by a lot.
Refer to Fig. 4-1. What is a preventative measure for when the circuit malfunctions? ANS:The fuse
blows, shutting off the power supply.
Why is troubleshooting easier with block diagrams? ANS:The technician can pay attention to the block
where the mistake is located.
What is the ac voltage and frequency of power available at ordinary wall outputs? ANS:120 V, 60 Hz
What component can be used to step down the voltage to the amount needed? ANS:Transformer
Why is the primary to secondary ratio for a transformer important? ANS:It represents the ratio between
the primary and secondary voltage.
Is the cathode connected to the positive or negative end of the load? ANS:Positive
What determines the load polarity? ANS:The diode polarity
If the negative or positive alternation of an ac signal is missing, what is it called? ANS:Half-wave
pulsating direct current
What determines which way the waveform will be shown in a rectifier circuit? ANS:If ground is on the
positive side of the load, the positive ac alternation will be blocked, but the negative ac alternation will
be blocked if ground is on the negative side.
If an oscilloscope is connected across the rectifier circuit, its ground lead will be ___________ , while its
probe tip will be ______________. ANS:Positive, negative
Are half-wave rectifiers used in high or low power applications? ANS:Low power
Do half wave rectifiers supply the output for half the time or half the power? Explain. ANS:Half the
power, which means less energy can be delivered in a given amount of time.
, What does a full wave rectifier use? ANS:It used a center tapped secondary and two diodes.
What does it mean when a winding is center tapped? ANS:The electrical center of the winding is
connected.
What fraction of the secondary voltage is supplied to a load due to the center tap? ANS:1/2
How much more power can a full wave rectifier deliver compared to a half wave rectifier? ANS:Twice as
much
Is load current the same or different for both alternations for rectified circuits? ANS:Same
Why is rectified ac considered dc? ANS:The direction of the current never changes.
Refer to Fig. 4-5. Which diode will be on during the positive alternation? ANS:D1
Refer to Fig. 4-5. Which diode will be on during the negative alternation? ANS:D2
What happens when the polarity of the diodes is reversed in a full wave rectifier circuit? ANS:The
polarity of the full wave pulsating direct current is reversed.
Is the fact that transformers must be center tapped for full wave rectifiers an advantage or
disadvantage? Why or why not? ANS:It is a disadvantage because transformers are large, heavy, and
expensive.
What is an advantage of bridge rectifiers? ANS:They offer full wave rectification without a transformer.
How many diodes does a bridge rectifier use? ANS:4
In a bridge rectifier, which direction do the current flow during the positive alternation? ANS:Left, right,
left
In a bridge rectifier, which direction do the current flow during the negative alternation? ANS:Right, left,
right
Which common point determines the polarity in the bridge rectifier circuit? ANS:The right or left end of
the load
Is the first alternation in a full-wave rectifier positive or negative? ANS:Negative
Is the second alternation in a full wave rectifier positive or negative? ANS:Positive
What does damping do to a meter? ANS:It limits the speed with which a pointer can change position.
Which Value of the PULSATING DC does the meter settle on? ANS:Average value
Which value of the AC supply voltages are spermicides by a meter? ANS:Rms value
What does RMS stand for? ANS:Root Mean Square
Applications Chapter 4
What does the power supply do? ANS:It changes the ac to a form compatible with the circuit such as dc.
What is a bipolar power supply? ANS:A power supply that supplies both positive and negative voltages
What does it mean if a power supply has a wide voltage tolerance? ANS:It means that its voltage may
vary by a lot.
Refer to Fig. 4-1. What is a preventative measure for when the circuit malfunctions? ANS:The fuse
blows, shutting off the power supply.
Why is troubleshooting easier with block diagrams? ANS:The technician can pay attention to the block
where the mistake is located.
What is the ac voltage and frequency of power available at ordinary wall outputs? ANS:120 V, 60 Hz
What component can be used to step down the voltage to the amount needed? ANS:Transformer
Why is the primary to secondary ratio for a transformer important? ANS:It represents the ratio between
the primary and secondary voltage.
Is the cathode connected to the positive or negative end of the load? ANS:Positive
What determines the load polarity? ANS:The diode polarity
If the negative or positive alternation of an ac signal is missing, what is it called? ANS:Half-wave
pulsating direct current
What determines which way the waveform will be shown in a rectifier circuit? ANS:If ground is on the
positive side of the load, the positive ac alternation will be blocked, but the negative ac alternation will
be blocked if ground is on the negative side.
If an oscilloscope is connected across the rectifier circuit, its ground lead will be ___________ , while its
probe tip will be ______________. ANS:Positive, negative
Are half-wave rectifiers used in high or low power applications? ANS:Low power
Do half wave rectifiers supply the output for half the time or half the power? Explain. ANS:Half the
power, which means less energy can be delivered in a given amount of time.
, What does a full wave rectifier use? ANS:It used a center tapped secondary and two diodes.
What does it mean when a winding is center tapped? ANS:The electrical center of the winding is
connected.
What fraction of the secondary voltage is supplied to a load due to the center tap? ANS:1/2
How much more power can a full wave rectifier deliver compared to a half wave rectifier? ANS:Twice as
much
Is load current the same or different for both alternations for rectified circuits? ANS:Same
Why is rectified ac considered dc? ANS:The direction of the current never changes.
Refer to Fig. 4-5. Which diode will be on during the positive alternation? ANS:D1
Refer to Fig. 4-5. Which diode will be on during the negative alternation? ANS:D2
What happens when the polarity of the diodes is reversed in a full wave rectifier circuit? ANS:The
polarity of the full wave pulsating direct current is reversed.
Is the fact that transformers must be center tapped for full wave rectifiers an advantage or
disadvantage? Why or why not? ANS:It is a disadvantage because transformers are large, heavy, and
expensive.
What is an advantage of bridge rectifiers? ANS:They offer full wave rectification without a transformer.
How many diodes does a bridge rectifier use? ANS:4
In a bridge rectifier, which direction do the current flow during the positive alternation? ANS:Left, right,
left
In a bridge rectifier, which direction do the current flow during the negative alternation? ANS:Right, left,
right
Which common point determines the polarity in the bridge rectifier circuit? ANS:The right or left end of
the load
Is the first alternation in a full-wave rectifier positive or negative? ANS:Negative
Is the second alternation in a full wave rectifier positive or negative? ANS:Positive
What does damping do to a meter? ANS:It limits the speed with which a pointer can change position.
Which Value of the PULSATING DC does the meter settle on? ANS:Average value
Which value of the AC supply voltages are spermicides by a meter? ANS:Rms value
What does RMS stand for? ANS:Root Mean Square
