Rectifiers and Battery Chargers Part A Flashcards
What does a typical DC meter measure? A) Average B) Instantaneous C) RMS D) Maximum
A) Average
What does a typical AC meter measure? A) Average B) Instantaneous C) RMS D) Maximum
C) RMS
What type of meter performs a continuity check on a circuit?
Ohmmeter
Does a digital ohmmeter with a reading OL indicate a short circuit or an open circuit?
Open Circuit
What type of ammeter doesn’t require the wiring of the circuit to be opened up and connected to the meter to measure the current?
Clamp-On Ammeter
What two things does a oscilloscope graph display?
Voltage and Time
If two scope leads each have a reference lead, should both reference leads be connected to the circuit or should one reference lead be isolated from the circuit?
One isolated
An AC voltage sine wave takes 8 divisions to complete one cycle. What is the period of the waveform?
8 ms
How many electrons does a semiconductor have in its valence shell?
4
What are the two types of doped semiconductive material called?
P-Type
N-Type
When light shines on a LDR what happens to its resistance?
A) Increases
B) Decreases
C) Stays the same
B) Decreases
Conventional current is considered to flow through a diode from:
A) Anode to Cathode
B) Cathode to Anode
A) Anode to Cathode
What is the barrier voltage of a silicone PN junction?
0.7 V
When is a diode forward biased?
A) When it is more positive on the Anode
B) When it is more positive on the Cathode
A) When it is more positive on the Anode
What is Vrrm?
Repetitive reverse maximum voltage
What is I f(av)
Average current when forward biased
What is I fsm
Instantaneous maximum forward surge current
What application of a diode prevents the destructive effects of CEMF When an inductive DC circuit is opened up?
A) Light emitting
B) Rectifier
C) Blocking
D) Freewheeling
D) Freewheeling
What application of a diode is used in a fire bell?
A) Light emitting
B) Rectifier
C) Blocking
D) Freewheeling
C) Blocking
In a P-type material the minority current carriers are the electrons.
True or False?
True
What is the purpose of a free wheeling diode?
A) prevent arcing at switches in inductive dc circuits.
B) absorb the cemf spike when a dc circuit is opened.
C) supply current to dc inductors when the supply is switched off.
D) suppress inductive reactance in ac circuits.
A) prevent arcing at switches in inductive dc circuits.
Electrons in the outermost shell are known as ____________ electrons.
Valence
Conductors have a very ______ electrical resistance.
Low
Electrons only loosely bound to the atom are called ______ _________.
Free electrons
Insulators have a very ______ electrical resistance.
High
Semiconductors posses four valence electrons and are referred to as ______________ elements.
Tetravalent
What are two common tetravalent elements found in semiconductors?
Silicon (Si)
Germanium (Ge)
What is covalent bonding?
Each atom shares its four valence electrons with the adjoining atoms, causing the material to act as if each atom had eight electrons in the outer shell.
Once intrinsic material has been doped, the result is __________ material.
Extrinsic
_____________ materials contain five valence electrons.
Pentavalent.
N-Type
_____________ materials contain three valence electrons.
Trivalent
P-Type
The bond between silicon atoms are called a _________ bond, and together the atoms form a _________ __________ structure.
The bond between silicon atoms are called a COVALENT bond, and together the atoms form a CRYSTAL LATTICE structure.
Silicon and germanium are __________ materials.
Tetravalent
Silicon is doped with ____________ atoms to form N-Type material.
Pentavalent
Silicon is doped with ____________ atoms to form P-Type material.
Trivalent
For a half-wave single phase rectifier, the DC current through the diode is _______ _____ the load current.
Equal too
Intrinsic silicon is doped with trivalent material the crystal lattice structure has a _________ charge.
Neutral
A PN junction is reversed biased. This PN junction develops a large ___________ region.
Barrier region;
Depletion region
For a diode to begin to conduct it must overcome the ________ ___________.
Barrier potential
A photo-diode is placed ________-bias in the circuit.
Reverse
A series ammeter has a ______ resistance.
Low
A voltmeter has a ______ resistance.
High
_______________ is the property of a material that exhibits a lower resistance when exposed to light energy.
Photoconduction
- Devices made of this material are photoconductive cells (photocells).
What is a MOV device?
Metal-Oxide-Varistor
- Type of surge suppressor; filters out voltage spikes that can occur on the AC supply.
____________ ___________ ____________ is instantaneous reverse bias voltage that can safely be applied to the diode.
Repetitive reverse maximum (Vrrm)
Press fit diodes are also known as __________ current diodes.
Medium
Diodes in the 150A to 500A range are usually ______ ________ with a pigtail
Stud mounted
Low current diodes are rated ___A or less
3A
Heat sinks are usually mounted vertically to make use of the ________ ________ in which air moves by convection over the fins.
Chimney effect
The largest current rating diodes are available in a shape called a _________ ____.
Hockey puk
The four most important electrical rating of diodes are:
- Maximum forward bias average current; I f(max)
- Repetitive reverse maximum; Vrrm
- Maximum instantaneous forward surge current; Ifsm or Ifm surge
- Forward voltage drop at rated current; Vf at rated If
The nucleus contains what two subatomic particles?
Protons and neutrons
What subatomic particle has a negative charge?
Electrons
How many electrons does an insulator have?
5 to 8
P-Type material has a net ________ charge.
Neutral
N-Type material is doped with ________-valent atoms
Pentavalent
When P-Type material is joined with N-Type material what device is created?
Diode (PN Junction)
Name two semiconductors materials
Silicon (0.7V)
Germanium (0.3V)
The term intrinsic means the material is _________.
Pure
The term extrinsic means the material has been _________.
Doped
Silicon is doped with trivalent atoms to form __-type material.
P-type
When an impurity is added to an intrinsic material it becomes ________ material.
Extrinsic
What is used to control the destructive effect of a Cemf spike caused by an inductive circuit?
Freewheeling diode
