# Need help with some multiple choice questions.

Discussion in 'Homework Help' started by FerrumIgnotus, Feb 9, 2012.

1. ### FerrumIgnotus Thread Starter New Member

Feb 9, 2012
5
0
Hello! I am in need of anwseres to those questions. As quickly as possible if possible. I know it is not nice to ask for things like that but I am in both time and sources of information loss. So Please, PLEASE solve them for me. Please.

The bipolar NPN transistor with Beta=200A/A works as a switch with emitter connected to the ground, and load R_C=4.8K connected between the collector and +5V potential. The transistor will be in saturation mode. a) For U_BE<UBET (I assume its U_BET) b) for I_b>5µA c) for I_b>0 d) for U_BE>0

The real current source has internal resistance of 50 Ohms. When shorted, it provides the current of 100 mA, this source may be replaced with: a) an ideal voltage source E=0.5V connected in series with resistance R=50 Ohms. b) an ideal voltage source E=5V connected in parallel with resistance R=50 Ohms. c) an ideal voltage source E=5V connected in series with resistance R=50 Ohms. d) an ideal voltage source E=0.5V connected in parallel with resistance R=50 Ohms.

The collector emitter voltage of the bipolar NPN transistor equals 12V. The collector current of the transistor equals 0mA. The transistor state is: a) passive b) saturated c) cut-off d) active.

If in a NPN transistor β= 50 and I_B, and this transistor is in saturation mode, then I_C meets the following condition a) I_C≤5mA b) I_C≥5mA c) I_C≥2µA d) I_C≤2µmA

If five equal resistors connected in series dissipate a total power of 20W, how much power does each resistor dissipate: a) 20W b) 100W c) 4W d) 5W

The unloaded voltage source develops the output voltage 5V. When loaded with resistance of 2kOhms the output voltage drops to 4V. What is the internal resistance of this voltage source? A)1kOhms b) 500Ohms c)2.5kOhms d)400Ohms

Which from the listed amplifiers is not suitable to amplify the DC component of the input signal
a) noniverting amplifier with op-amp, b) inverting amplifier with op-amp, c) Differential amplifier, d) Common emitter or common source amplifier,

If five equal resistors connected in series dissipate a total power of 20W, how much power does each resistor dissipate: a)20W, b)100W, c) 4W, d) 5W

In the NPN transistor, beta=200A/A, IC=1mA, IB=10μA a) transistor works in saturation state b) transistor works in active state c) this is impossible d) transistor works in cutoff state

The unloaded voltage source develops the output voltage 3V. When loaded with resistance of 2kΩ, the output voltage drops to 1V. What is the internal resistance of this voltage source? a) 6kΩ, b) 2kΩ, c) 4kΩ, d) 1kΩ

2. ### justtrying Active Member

Mar 9, 2011
329
405
when in doubt the answer for multiple choice c)

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When posting a request for homework/coursework/assignment help, you must provide details of your attempts at the questions. Any thread that just posts up a copy of the questions without any attempts on the part of the opening poster will be directed to this thread and will be given 48 hours to satisfy the requirements detailed within. Help us, help you."

3. ### FerrumIgnotus Thread Starter New Member

Feb 9, 2012
5
0
I was aware of that. The problem being that a) i dont have time b) I study computer science with the main idea being programming, but in my first semester i have Electronic Principles, tommorow I have a test. c) My professor isn't exacly the prime of teaching and/or exchaning sources of knowledge. Now, while knowing the position I am in, will You kindly solve them? To give you some encouragment I will tell You that currently its 1:30 am and I am falling asleep and I have already SOLVED three fourths of this test. These are the questions I had problem with.

4. ### justtrying Active Member

Mar 9, 2011
329
405
then it is time to go to sleep

5. ### FerrumIgnotus Thread Starter New Member

Feb 9, 2012
5
0
Superposition theoreom only applicable to: linear circuits.
The current source may be replaced in a model of circuit with an equivalent voltage source only when it is in a non-ideal source.
Which of the below connections is not acceptable in a model of a circuit: series connection of two ideal current sources with different output currents
The capacitor in a DC current circuit behaves: like an open circuit.
The ideal inductance in an DC current circuit behaves: like a short circuit.
In the unloaded voltage divider consisting of two resistors: the higher voltage develops on higher resistance.
In the current divider consisting of two resistors: the higher current flows through the resistor with lower resistance.
The circuit works in the operating point Q. The small signal voltage gain of the circuit is: horizontal minus vertical.
In the NPN transistor, beta=200A/A, IC=1mA, IB=10μA: transistor works in saturation mode.
Which from the listed amplifiers is NOT suitable to amplify the DC component of the input signal: common emitter or common source amplifier.
We want to use the MOSFET transistor as a switch to turn on and off the load. (eg. Electric motor). We want to minimize power loss in the switch. The transistor should be switched between: linear mode and cutoff mode.
R_C is loaded with R_0 via C_2 : f_t 1/(2πC_2 (R_C+R_0))
Electrical current is defined as: the rate of flow of charge carriers.
The 4 1⁄2 digit meter displays a value of 0.50000 the measurement range is: 2v
In order to measure the current in a circuit an ammeter must be inserted into the circuit so the current flows through it.
The small variation in the output voltage of a DC power supply is called: ripple voltage.
When the drain resistor in the common source amplifier is decreased in value the voltage gain decreases.
One of the advantages of Darlington pair is: less cost.
The switched mode voltage regulators are used because : they offer better efficiency tan the linear ones.

These are the ones I solved.

6. ### FerrumIgnotus Thread Starter New Member

Feb 9, 2012
5
0
, even though I did prove I learned it, didnt manage to get any help from here. Am kinda sad, I can fail to pass the semester because of not getting the help. Well, I better keep my hopes up. About passing. Wish me luck.

7. ### t06afre AAC Fanatic!

May 11, 2009
5,939
1,222
In this part of the forum. We do not just serve a solution on a silver plate. You must at least show some effort. Had you just written some lines like "I think answer X is correct because .....et cetera" You would have got the help you needed. But anyway good luck

8. ### FerrumIgnotus Thread Starter New Member

Feb 9, 2012
5
0
I answered 9 out of 10 questions. If i get 1 wrong, I wont pass, but luckily, I think I was able to answer all of them correctly. And non of them were those I had problems with. Well, next time, if there will be one, I will post for help here earlier. Had I the time, I would have fulfilled all the requirements needed for help.

9. ### justtrying Active Member

Mar 9, 2011
329
405
and do not leave things to last minute. Along with professionals and instructors, there are students just like you, in exactly the same situation, trying to help each other. Good luck.