0
In bjt small signal analysis in emitter stablization bias the circuit which have re unbypassed when trying to get zb the impedance why you divided vi by ib although that that both resistances beta r?
Wiki User
∙ 14y ago
//you tell us and we'll both know
assuming that you have used h-parameter analysis for this ...Vb contains the Ib and the Ie terms which can be expressed ad Ie=(1+Hfe)Ib
then we have
Vb=Hie*Ib + Re*Ie
=Hie*Ib + Re(1+Hfe)Ib
=Ib(Hie+(1+Hfe) Re)
then we can find
Ri as Vb/Ib= Hie+(1+Hfe)*Re
hope that helps....
Wiki User
∙ 14y ago
Add your answer:
Earn +20 pts
What is affect of using a 3 ohm speaker with a 100 Watt amplifier?
Amplifier power and impedance are not related, although a lower impedance speaker will be louder. Most home stereos cannot drive loads below 4 ohms, however, so using this 3 ohm speaker with a home theater may cause the amp to go into protection mode or shut down completely. Check your owner's manual to see what impedance of speaker your receiver can safely drive.
What should be real and reactive power flow through the transmission line when the sending end and receiving end voltages are of same magnitudes and phase angles?
The power transfer equation is this:P = V1*V2*sin(phi)/Xt,V1 = source 1 voltageV2 = source 2 voltagephi = angle between the two sourcesXt = transfer impedance, the impedance of the line + both source impedancesFrom this you can see that if the angle between the two sources is 0, then the power transferred would be zero as well.Reactive power flow *should* be zero if perfectly matched as well, although there will be a small amount of reactive power usage due to line charging (charging current).
What if the fourth wire in a three phase is having impedance would the current in the neutral line remain to have a value of zero?
When the system is in balance, with three equal phase currents, there is no current in the neutral 4th wire and it is not needed. However if the load is unbalanced, the neutral is needed to maintain the star point at zero volts.So for example a street of houses fed by a 3-phase supply needs a neutral because the houses draw unequal currents from the different phase lines, although a large enough collection of houses would tend to balance itself out.If a three-pase system has equal currents the current in the neutral is zero. If two phases draw equal current but the third has no load, there is an equal current in the neutral, and if one phase draws current but the other two have no load, there is again an equal current in the neutral.ANOTHER ANSWERA three-phase, four-wire, system comprises three line conductors and a neutral conductor. If the load supplied by this system is balanced (i.e. the loads connected between each line and neutral are identical in all respects), then no current will flow in the neutral conductor regardless of its impedance. If the load is unbalanced, then a neutral current will flow in the neutral conductor. In other words, the impedance of the neutral conductor plays no part in whether or not there is a neutral current.
What is neutral earth compensator?
For earth fault protection on the windings of a delta connected transformer. Used in MV distribution. An earth fault current return path is provided by connecting a Neutral Earthing Compensator (NEC) between the three phases of the power system and the earth system. This is done at the source of the supply. The NEC transformer winding has a Zig-zag configuration with no secondary winding. The impedance of the winding is high when there is no fault on the system resulting in only a small magnetising current in the transformer windings. The Zig-zag winding configuration results in a low impedance when an earth fault condition occurs. By inserting resistance between the neutral of the Zig-zag transformer and earth, the earth fault currents can be limited to any desired value. The resistance value and rating has been standardised to allow an earth fault current of 300 amp for 10 seconds, although some older installations may still operate at the old standard of 600 amps.
If you attempted to read the voltage across a car battery with the multimeter accidentally in ammeter mode?
A multimeter when used on voltage, has a very high resistance/impedance to limit the current flowing through it. However when you set it to read current, it has a very small resistance to encourage the current to flow through the metre so can be measured. So ig you put a multimeter across a voltage source (in parrallel) when its set to current, you will normally destroy the metre. Although more expensive metres will have a fuse to protect the instrument should this occur. Hope this helps Always switch back, should you do this on the mains, you can quite easily set the metre on fire!! CB Eng
Can i plug my 4 ohms Guitar amp into 16 ohms speakers?
That should be safe; although you won't get the best out of the loudspeakers. It's a myth. There is really no 16 Ohm amplifier on the market. And there never was. The amplifier will have an output impedance of around 0.04 ohms. In hi-fi we have always impedance bridging. Zout << Zin. That means the output impedance of the amplifier is much less than the input impedance of the loud speaker. The damping factor Df = Zin / Zout tells you what Zout is. Zout = Zin/Df. If the damping factor Df = 200 and the loudspeaker impedance is Zin = 16 ohms, the output impedance of the amplifier is Zout = 16 / 200 = 0.08 ohms. You see, there is no "16 ohm amplifier" on the market with a 16 ohm output impedance. Scroll down to related links and look at "Voltage Bridging or impedance bridging - Zout < Zin".
Can an 8 ohm amp drive 16 ohm speakers?
Never heard of a 16 ohm hifi aplifier. All amplifiers have an output impedance of less than 0.1 ohm. We use always impedance matching with a low source impedance to the much higher load impedance. Scroll down to related links and read "Amplifier, Loudspeaker, and Ohms".
What is affect of using a 3 ohm speaker with a 100 Watt amplifier?
Amplifier power and impedance are not related, although a lower impedance speaker will be louder. Most home stereos cannot drive loads below 4 ohms, however, so using this 3 ohm speaker with a home theater may cause the amp to go into protection mode or shut down completely. Check your owner's manual to see what impedance of speaker your receiver can safely drive.
Does the impedance of an RL series circuit varies inversely with the frequency?
The simple answer is no. The impedance of an R-Lcircuit is the vector sum of the circuit's resistance and its inductive reactance. Resistance is determined by the length, cross-sectional area, and resistivity of the conductor (although its 'a.c. resistance' is proportional to the frequency squared), whereas the inductive reactance is directly proportional to the frequency of the supply.
Is it possible to develop an immunity to Salmonella?
Although one cannot be completely immune to salmonella, humans can develop resistances against it. Whether you get sick or not from eating foods infected with salmonella depends upon your bodies inherent and developed resistance against it and the strain of salmonella in the food you are consuming.
What is stray capacitance and how is different from ordinary capacitor?
Any two adjacent conductors can be considered a capacitor, although the capacitance will be small unless the conductors are close together for long. This (often unwanted) effect is termed "stray capacitance". Stray capacitance can allow signals to leak between otherwise isolated circuits (an effect called crosstalk), and it can be a limiting factor for proper functioning of circuits at high frequency. Stray capacitance is often encountered in amplifier circuits in the form of "feedthrough" capacitance that interconnects the input and output nodes (both defined relative to a common ground). It is often convenient for analytical purposes to replace this capacitance with a combination of one input-to-ground capacitance and one output-to-ground capacitance. (The original configuration - including the input-to-output capacitance - is often referred to as a pi-configuration.) Miller's theorem can be used to effect this replacement. Miller's theorem states that, if the gain ratio of two nodes is 1/K, then an impedance of Z connecting the two nodes can be replaced with a Z/(1-k) impedance between the first node and ground and a KZ/(K-1) impedance between the second node and ground. (Since impedance varies inversely with capacitance, the internode capacitance, C, will be seen to have been replaced by a capacitance of KC from input to ground and a capacitance of (K-1)C/K from output to ground.) When the input-to-output gain is very large, the equivalent input-to-ground impedance is very small while the output-to-ground impedance is essentially equal to the original (input-to-output) impedance.
What is voltage follower?
A voltage buffer amplifier is used to transfer a voltage from a first circuit, having a high output impedance level, to a second circuit with a low input impedance level.If the voltage is transferred unchanged (the voltage gain Av is 1), the amplifier is a unity gain buffer; also known as a voltage follower because the output voltage follows or tracks the input voltage. Although the voltage gain of a voltage buffer amplifier may be (approximately) unity, it usually provides considerable current gain and thus power gain
What is working principle of inductor?
A changing current through an inductor induces a voltage into the inductor, the direction of which always opposes the change in that current.So, in a d.c. circuit, an inductor will oppose (not prevent) any rise or fall in current, although the magnitude of that current will be determined by the resistance of that inductor, not by its inductance.In an a.c. circuit, because the current is continuously changing both in magnitude and in direction, it acts to continuously oppose the current due to its inductive reactance. Inductive reactance is proportional to the inductance of the inductor and the frequency of the supply. The vector sum of the inductive reactance of the inductor and the resistance of the inductor, is termed the impedance of the inductor. Inductive reactance, resistance, and impedance are each measured in ohms.
What should be real and reactive power flow through the transmission line when the sending end and receiving end voltages are of same magnitudes and phase angles?
The power transfer equation is this:P = V1*V2*sin(phi)/Xt,V1 = source 1 voltageV2 = source 2 voltagephi = angle between the two sourcesXt = transfer impedance, the impedance of the line + both source impedancesFrom this you can see that if the angle between the two sources is 0, then the power transferred would be zero as well.Reactive power flow *should* be zero if perfectly matched as well, although there will be a small amount of reactive power usage due to line charging (charging current).
How does gravity oppose light?
Although photons do not demonstrate the ability to generate gravity, their paths can be affected by the warping of the space through which they travel. This phenomena is known as gravitational lensing, and can make an object appear to be in two different locations at the same time. The impedance of light from a black hole is not caused by a direct gravitational attraction. Rather the emitted light is curved back into the black hole. It may be, as some suggest, that "gravity makes night fall".
What is another word you can use instead of and?
although Although although is like but, furthermore better resembles and.
What is the correct form Although this is good or Although this be good?
The phrase "although this is good" would be correct modern English; the phrase "although this be good" is archaic.
