Answer the Below Question with Proper Explanation only. Without explanation I ca
ID: 2988344 • Letter: A
Question
Answer the Below Question with Proper Explanation only. Without explanation I cant justify the answer and I wont provide the points.
Select the answer from the code given below:
Assertion (A) : Thevenin's theorem is normally used to find the equivalent voltage source and. Thevenin's equivalent resistance of a complex network.
Reason (R) :Thevenin theorem holds good for d.c.voltages but not for a.c voltages.
Assertion (A) :In the normal operation of BJT the emitter diode and collector diode are forward biased.
Reason (R) :In the active region the BJT can provide class-A operation.
Assertion (A):Helical antenna can be used as feeder for large parabolic reflectors to obtain circular polarization.
Reason (R) :Parabolic reflectors reverse the sense of polarization of the wave during reflection.
Explanation / Answer
1. Thevenin's theorem is used find equivalent voltag esource in series with equivalent resistance of a linear bilateral circuit having multiple sources and resistances/ impedances. This can be applied both for D.C voltgaes and A.C voltages.
So, answer is (3), A is TRUE, R is FALSE
2. In the normal operation of BJT, it will operate in Active region in which the emitter diode is Forward biased and collector diode is Reverse biased.
Class A operation can only be obtained when the transistor spends its entire time in the active mode, never reaching either cutoff or saturation.
So, answer is (4), A is FALSE, R is TRUE
3. Helical antennas have long been popular in applications from VHF to microwaves requiring circular polarization, since they have the unique property of naturally providing circularly polarized radiation.
reflection from the parabolic reflector reverses the sense of circular polarization, so that the reflection coming back into the horn will appear at the other port and reduce the isolation.
So, the answer is (2) Both (A) and (R) are true, but (R) is not the Correct explanation of (A).