Zener diodes are also known as
a) Voltage regulators
b) Forward bias diode
c) Breakdown diode
d) None of the mentioned
…………
Answer: c
Explanation: Zener diodes are used as voltage regulators but they aren’t called voltage regulators. They are called breakdown diodes since they operate in breakdown region.
Which of the following can be used in series with a Zener diode so that combination has almost zero temperature coefficient?
a) Diode
b) Resistor
c) Transistor
d) MOSFET
………….
Answer: a
Explanation: If a Zener diode of TC of about -2mV is connected with a forward diode (which has a TC of about +2mV) in series, the combination can be used to obtain a very low (close to zero) TC.
What is the effect of an inductor filter on a multi frequency signal?
a) Dampens the AC signal
b) Dampens the DC signal
c) To reduce ripples
d) To change the current
……….
nswer: a
Explanation: Presence of inductor usually dampens the AC signal. Due to self induction induces opposing EMF or changes in the current.
The ripple factor (ϒ) of inductor filter is_________
a) ϒ = RZ3/√2ωL
b) ϒ = RZ/3√2ωL
c) ϒ = RZ3√2/ωL
d) ϒ = RZ3/√2ωL
…………..
Answer: b
Explanation: Ripple factor will decrease when L is increased and RL. Inductor has a higher dc resistance. It depends on property of opposing the change of direction of current.
The inductor filter gives a smooth output because_________
a) It offers infinite resistance to ac components
b) It offers infinite resistance to dc components
c) Pulsating dc signal is allowed
d) The ac signal is amplified
…………
Answer: a
Explanation: The inductor does not allow the ac components to pass through the filter. The main purpose of using an inductor filter is to avoid the ripples. By using this property, the inductor offers an infinite resistance to ac components and gives a smooth output.
The output of a rectifier is pulsating because_________
a) It has a pulse variations
b) It gives a dc output
c) It contains both dc and ac components
d) It gives only ac components
…………..
Answer: c
Explanation: For any electronic devices, a steady dc output is required. The filter is used for this purpose. The ac components are removed by using a filter.
The output voltage VDC for a rectifier with inductor filter is given by_________
a) (2Vm/π)-IDCR
b) (2Vm/π)+IDCR
c) (2Vmπ)-IDCR
d) (2Vmπ)+IDCR
……………
Answer: a
Explanation: The inductor with high resistance can cause poor voltage regulation. The choke resistance, the resistance of half of transformer secondary is not negligible.
What causes to decrease the sudden rise in the current for a rectifier?
a) the electrical energy
b) The ripple factor
c) The magnetic energy
d) Infinite resistance
………….
Answer: c
Explanation: When the output current of a rectifier increases above a certain value, magnetic energy is stored in the inductor. This energy tends to decrease the sudden rise in the current. This also helps to prevent the current to fall down too much.