4.For Tutor Adil B Only! For Tutor Adil B Only! For Tutor Adil B Only! For Tutor Adil B Only! For Tutor Adil B Only!
7.Photon has mass or not? I am confused, since we say, it has zero rest mass but how does it is affected by gravity then?
Power electronics deals in the design, development, control and transformation of power in the electrical form of energy. Power electronic system converts electrical energy into electric load through a control circuit. It involves the processing of high voltages and currents to deliver power as an output. The application of power electronics ranges from AC/DC converters, semiconductor devices to inverters.
Question 1: Which of the following is true in case of forward biased p-n junction diodes?
a) The positive terminal of the battery takes electrons from the p-region
b) The positive terminal of the battery injects electrons into the p-region
c) The negative terminal of the battery takes electrons from the p-region
d) None of these
Answer: a) The positive terminal of the battery takes electrons from the p-region
Explanation: Since the diode is forward biased, the positive side is connected to p and vice versa.
Question 2: ___________ are the majority carriers in n-type material.
a) Protons b) Electrons
c) Charges d) None of these
Answer: b) Electrons
Explanation: The n-region has greater concentration of electrons as compared to the p-region in a P-N junction diode.
Question 3: Find the average value of output current for a 1-phase HW diode rectifier with R load, having RMS output current of 200 A.
Question 4: In a three phase diode half wave rectifier using 3 diodes, each diode conducts for _______ degree at a time.
a) 60 b) 120
c) 180 d) 270
Answer: b) 120
Explanation: In a three phase diode half wave rectifier, only one diode conducts at a time.
Question 5: Find the average gate power dissipation when the maximum allowable gate power dissipation is 20 KW, with a duty cycle 50%.
a) 2 KW b) 5 KW
c) 10 KW d) 15 KW
Question 6: The duty cycle can be written in the form of
a) fT b) f/T
c) T/f d) T
Answer: a) fT
Explanation: Given, Pulse on period = T, Periodic time = f
Question 7: Find the triggering frequency when the average gate power dissipation is 0.6 W and the peak gate drive power is 10 Watts. The gate source has a pulse width of 20μsec duration.
a) 1000 Hz b) 2000 Hz
c) 3000 Hz d) 5000 Hz
Answer: c) 3000 Hz
Question 8: A ____________ is used to control the dc voltage to the inverter.
a) Transformer b) Chopper
c) Converter d) All of the above
Answer: b) Chopper
Explanation: External control of dc voltage is obtained by the use of a chopper, which gets further converted from variable dc to variable ac by the converters.
Question 9: Before the invention of semiconductor technology _________ devices were used for the voltage control applications.
a) Induction machine b) Inverters
c) Tap changing transformer d) None of these
Answer: c) Tap changing transformer
Explanation: Tap changing transformer can give variable ac from fixed ac without a change in frequency.
Question 10: ___________ controllers are used in electrical heating applications.
a) DC voltage b) AC voltage
c) Both (a) and (b) d) None of these
Answer: b) AC voltage
Explanation: Variable ac supply is required for electrical heating. The devices are fired to apply enough temperature.