Answer the Below Question with Proper Explanation only. Without explanation I ca
ID: 2988348 • 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) : In a constant voltage source, the internal impedance of the voltage source is very low as compared to the load impedance.
Reason (R) : The lesser the ratio of Zi/ZL , the better is the source as a constant voltage source.
Assertion (A) : A circuit containing reactances is said to be in resonance if the voltage across the circuit is inphase with the current through it.
Reason (R) :At resonance, the power factor of the circuit is zero.
Assertion (A) : A switched mode power supply is a high efficiency dc-dc converter with an unregulated input dc voltage and a regulated output voltage.
Reason (R) : The efficiency is higher because transistors are used between ON and OFF states.
Explanation / Answer
Assertion1 :states that the internal impedence of an constant voltage source is less than external its true because we have a condition that for an ideal voltage source the internal impedence is zero which is not possible in real world but the most we try to make it less the more it reaches the ideal characteristics hence the reason1: that Zi/Zl should be small means that external impedance should be greater than the internal impedance and that is supporting the Assertion so for this Assertion 1 and reason 1 are true and A is supported by R
Assertion 2: for any circuit to be in resonance the main factor is that the voltage should be in phase with the current if that doesnot happen then resonance occurance is very low possibility so the assertion is true
Reason2: when any ciruit is in resonance the power factor is 1 but not zero
The power factor of an RLC circuit under resonance is 1.
Explaination:- Powerfactor of an RLC
circiut is given by=R/|Z| For a resonant circiut,|Z|=R
Because reactive components are zero in resonance) . . .Power factor=R/R=1.
Voltage and current are in phase (unity power factor).
hence the assertion2 is true and reason2 is false
Assertion3: A switch mode power supply circuit can be used to:
Step up or step down an unregulated dc input voltage to a regulated dc output voltage
Step up an unregulated dc input voltage to a regulated dc output voltage using a Boost Converter circuit or
Step-Up SMPS
Step down an unregulated dc input voltage to a regulated dc output voltage using a Buck Converter circuit or
Step-Down SMPS,
Invert the input dc voltage using usually a Cuk converter circuit , and
Produce multiple dc outputs using a the fly-back converter circuit.
Switch mode power supply is a widely used in a system such as a computer, television receiver, battery charger etc. The switching frequency above than 20 kHz is used in SMPS, so noise produced is above the audio range.It is used in high-frequency unity-power factor circuit. It is also used to produce a variable dc voltage to a dc motor armature in a variable speed drive.
Advantages of SMPS:
Greater efficiency because the switching transistor dissipates little power means the transistors are used between on and off states thus
the Assertion 3 and reason 3 are true and A is supported by R