Diodes And Applications MCQs

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A characteristic curve is the result of a current versus voltage plot of diode activity, which begins at the:

  • A. 3rd quadrant
  • B. current plot
  • C. graph origin
  • D. voltage plot
  • Correct Answer: Option C

A filtered full-wave rectifier voltage has a smaller ripple than does a half-wave rectifier voltage for the same load resistance and capacitor values because:

  • A. there is a shorter time between peaks
  • B. there is a longer time between peaks
  • C. the larger the ripple, the better the filtering action
  • D. none of the above
  • Correct Answer: Option A

A two-diode rectifier will not operate without a _________.

  • A. center-tapped transformer
  • B. voltage regulator
  • C. capacitive filter
  • D. phase-inverting transformer
  • Correct Answer: Option A

An IC regulator receives an overload; it will:

  • A. shut down
  • B. compensate for heat
  • C. provide more voltage
  • D. sample and adjust
  • Correct Answer: Option A

DC power should be connected to forward bias a diode as follows:

  • A. – anode, + cathode
  • B. – cathode, – anode
  • C. + anode, – cathode
  • D. + cathode, + anode
  • Correct Answer: Option C

If a 169.7 V half-wave peak has an average voltage of 54 V, what is the average of two full-wave peaks?

  • A. 119.9 V
  • B. 108.0 V
  • C. 115.7 V
  • D. 339.4 V
  • Correct Answer: Option B

In a diode schematic, the anode is represented by a(n):

  • A. triangle
  • B. vertical line
  • C. zig-zag line
  • D. element indicator
  • Correct Answer: Option A

In a power supply diagram, which block indicates a pulsating dc output?

  • A. transformer
  • B. filter
  • C. rectifier
  • D. regulator
  • Correct Answer: Option C

In a power supply diagram, which block indicates a smooth dc output?

  • A. transformer
  • B. filter
  • C. rectifier
  • D. regulator
  • Correct Answer: Option D

List three diode packages:

  • A. clip package, DIP, small current package
  • B. DIP, small current package, large current package
  • C. small current package, large current package, and SIP
  • D. small current package, large current package, clip package
  • Correct Answer: Option D

Providing a constant output regardless of ac input or load resistance changes is the function of a:

  • A. transformer
  • B. filter
  • C. regulator
  • D. rectifier
  • Correct Answer: Option C

Rectifier output polarity depends upon:

  • A. cycles of input
  • B. capacitor polarity
  • C. half or full wave
  • D. diode installation
  • Correct Answer: Option D

Shunting the ac component away from the load is the task of a:

  • A. transformer
  • B. filter
  • C. regulator
  • D. rectifier
  • Correct Answer: Option B

Since diodes are destroyed by excessive current, circuits must have:

  • A. higher voltage sources
  • B. current limiting resistors
  • C. more dopants
  • D. higher current sources
  • Correct Answer: Option B

The average value of the half-wave rectified output voltage is approximately __________ of Vp.

  • A. 31.8%
  • B. 63.6%
  • C. 70.7%
  • D. 100%
  • Correct Answer: Option A

The dc current through each diode in a bridge rectifier equals:

  • A. the load current
  • B. half the dc load current
  • C. twice the dc load current
  • D. one-fourth the dc load current
  • Correct Answer: Option A

The diode schematic arrow points to the:

  • A. trivalent-doped material
  • B. positive axial lead
  • C. anode lead
  • D. cathode lead
  • Correct Answer: Option D

The mimicking of an open/closed switch by a diode allows alternating current to be:

  • A. rectified
  • B. regulated
  • C. controlled
  • D. attenuated
  • Correct Answer: Option A

The peak inverse voltage (PIV) across a nonconducting diode in a bridge rectifier equals approximately:

  • A. half the peak secondary voltage
  • B. twice the peak secondary voltage
  • C. the peak value of the secondary voltage
  • D. four times the peak value of the secondary voltage
  • Correct Answer: Option C

The small amount of ac signal present on the output of a filtering network for a dc power supply is known as ________.

  • A. pulsating dc
  • B. trickle
  • C. ripple
  • D. waffle
  • Correct Answer: Option C

Thermal shutdown occurs in an IC regulator if:

  • A. power dissipation is too high
  • B. internal temperature is too high
  • C. current through the device is too high
  • D. load resistance increases
  • Correct Answer: Option B

Typically the forward voltage on an LED is between _______ and ________.

  • A. 1.5 V, 3.7 V
  • B. 0.7 V, 1.1 V
  • C. 1 V, 3 V
  • D. 1 V, 6 V
  • Correct Answer: Option C

What circuit activity may shift a characteristic curve so that diode operating points are different?

  • A. higher power (heat)
  • B. higher resistance
  • C. lower voltage
  • D. lower current
  • Correct Answer: Option A

What is a varistor?

  • A. a voltage-dependent resistor
  • B. a voltage-dependent diode
  • C. a current-dependent resistor
  • D. a current-dependent diode
  • Correct Answer: Option A

What is the percent of regulation if Vnl = 20 V and Vfl = 19.8 V?

  • A. 0%
  • B. 1%
  • C. .1%
  • D. 5%
  • Correct Answer: Option B

When a diode is destroyed it has infinite impedance. When damaged by heat it will probably:

  • A. short
  • B. conduct more
  • C. conduct less
  • D. open
  • Correct Answer: Option A

When checking a diode, low resistance readings both ways indicate the diode is:

  • A. open
  • B. satisfactory
  • C. faulty
  • D. not the problem
  • Correct Answer: Option C

Which type of transformer is required to create a 180 degree input to a rectifier?

  • A. center-tapped secondary
  • B. step-down secondary
  • C. stepped-up secondary
  • D. split winding primary
  • Correct Answer: Option A

Why is heat produced in a diode?

  • A. due to current passing through the diode
  • B. due to voltage across the diode
  • C. due to the power rating of the diode
  • D. due to the PN junction of the diode
  • Correct Answer: Option A

With a 12 V supply, a silicon diode, and a 370-ohm resistor in series, what voltage will be dropped across the diode?

  • A. 0.3 V
  • B. 0.7 V
  • C. 0.9 V
  • D. 1.4 V
  • Correct Answer: Option B

With a half-wave rectified voltage across the load resistor, load current flows for what part of a cycle?

  • A. 0 degrees
  • B. 90 degrees
  • C. 180 degrees
  • D. 360 degrees
  • Correct Answer: Option C

With full-wave rectification, current through the load resistor must be:

  • A. in opposite directions
  • B. to the external load
  • C. from the reverse biased diode
  • D. in the same direction
  • Correct Answer: Option D