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WorksheetsFinal Examination: Power Electronics
Total questions: 35
Worksheet time: 18mins
Which of the following devices does not belong to the transistor family?
IGBT
MOSFET
GTO
BJT
A power transistor is a
three layer, three junction device
three layer, two junction device
two layer, one junction device
four layer, three junction device
In a power transistor, ____ is the controlled parameter.
VBE
VCE
IB
IC
A power transistor is a _________ device.
two terminal, bipolar, voltage controlled
two terminal, unipolar, current controlled
three terminal, unipolar, voltage controlled
three terminal, bipolar, current controlled
In a power transistor, _________ is the controlling parameter.
VBE
VCE
IB
IC
In a power transistor, the IB vs VBE curve is
a parabolic curve
an exponentially decaying curve
resembling the diode curve
a straight line Y = IB
For a power transistor, if the base current IB is increased keeping VCE constant, then
IC increases
IC decreases
IC remains constant
none of the mentioned
The forward current gain α is given by
IC/IB
IC/IE
IE/IC
IE/IB
The value of β is given by the expression
IC/IB
IC/IE
IE/IC
IE/IB
A power BJT is used as a power control switch by biasing it in the cut off region (off state) or in the saturation region (on state). In the on state
both the base-emitter & base-collector junctions are forward biased
the base-emitter junction is reverse biased, and the base collector junction is forward biased
the base-emitter junction is forward biased, and the base collector junction is reversed biased
both the base-collector & the base-emitter junctions are reversed biased
The power electronics devices have a very high efficiency because
cooling is very efficient
the devices traverse active region at high speed & stays at the two states, on and off
the devices never operate in active region
the devices always operate in the active region
For a power transistor, which of the following relations is true?
Ie>Ic>Ib
Ib>Ic>Ie
Ic>Ie>Ib
Ie=Ib
High frequency operation of any device is limited by the
forward voltage rating
switching losses
thermal conductivity
heat Sink arrangements
The instantaneous power loss during the delay time of a transistor is given by
Ic Vce
Ib Vbe
Ic Vbe
Ib Vce
Choose the correct statement
A transistor will remain on as long the the base current is applied
A transistor remains on after a high to low pulse is applied at the base
A transistor will remain on as long the the collector current is applied
A transistor remains on after a high to low pulse is applied at the collector
Let’s say that a transistor is operating at the middle of the load line, then a decrease in the current gain would
move the Q point up
move the Q point down
result in to & fro motion of the Q point
not change the Q point
The MOSFET combines the areas of _______ & _________
field effect & MOS technology
semiconductor & TTL
mos technology & CMOS technology
none of the mentioned
Which of the following terminals does not belong to the MOSFET?
Drain
Gate
Base
Source
Choose the correct statement
MOSFET is a uncontrolled device
MOSFET is a voltage controlled device
MOSFET is a current controlled device
MOSFET is a temperature controlled device
Choose the correct statement(s)
i) The gate circuit impedance of MOSFET is higher than that of a BJT
ii) The gate circuit impedance of MOSFET is lower than that of a BJT
iii) The MOSFET has higher switching losses than that of a BJT
iv) The MOSFET has lower switching losses than that of a BJT
Both i & ii
Both ii & iv
Both i & iv
Only ii
Choose the correct statement
MOSFET is a unipolar, voltage controlled, two terminal device
MOSFET is a bipolar, current controlled, three terminal device
MOSFET is a unipolar, voltage controlled, three terminal device
MOSFET is a bipolar, current controlled, two terminal device
The arrow on the symbol of MOSFET indicates
that it is a N-channel MOSFET
the direction of electrons
the direction of conventional current flow
that it is a P-channel MOSFET
In the internal structure of a MOSFET, a parasitic BJT exists between the
source & gate terminals
source & drain terminals
drain & gate terminals
there is no parasitic BJT in MOSFET
In the transfer characteristics of a MOSFET, the threshold voltage is the measure of the
minimum voltage to induce a n-channel/p-channel for conduction
minimum voltage till which temperature is constant
minimum voltage to turn off the device
none of the above mentioned is true
The output characteristics of a MOSFET, is a plot of
Id as a function of Vgs with Vds as a parameter
Id as a function of Vds with Vgs as a parameter
Ig as a function of Vgs with Vds as a parameter
Ig as a function of Vds with Vgs as a parameter
The GTO (gate turn-off thyristor) is a
p-n-p-n device
p-n-p device
p-metal-n device
p-n single junction device
The GTO can be turned off
by a positive gate pulse
by a negative gate pulse
by a negative anode-cathode voltage
by removing the gate pulse
The anode current is ideally limited by the
gate pulse amplitude
internal impedance of the device
load Impedance
gate circuit impedance
Choose the correct statement:
GTOs have _________ as compared to the CTs.
less on-state voltage drop
less gate drive losses
higher reverse blocking capabilities
faster switching speed
At turn-on the initial delay or turn on delay is the time required for the
input inductance to charge to the threshold value
input capacitance to charge to the threshold value
input inductance to discharge to the threshold value
input capacitance to discharge to the threshold value
Which among the following devices is the most suited for high frequency applications?
BJT
IGBT
MOSFET
SCR
Choose the correct statement
MOSFET suffers from secondary breakdown problems
MOSFET has lower switching losses as compared to other devices
MOSFET has high value of on-state resistance as compared to other devices
All of the mentioned
Choose the correct statement
MOSFET has a positive temperature co-efficient
MOSFET has a high gate circuit impedance
MOSFET is a voltage controlled device
All of the mentioned
Consider an ideal MOSFET. If Vgs = 0V, then Id = ?
Zero
Maximum
Id(on)
Idd
How does the MOSFET differ from the JFET?
JFET has a p-n junction
They are both the same
JFET is small in size
MOSFET has a base terminal
