Tagged Questions
0
votes
1answer
22 views
Fitting a circuit scheme to a simpler model
I have to simulate the electric field within a gas filled discharge gap generated by a radio frequency voltage generator. The circuit, provided to me by the experimenters somewhat far away, is given ...
0
votes
1answer
36 views
Current in AC circuit
The problem is to find the current on the capacitor. $I''$ should be correct, but I don't know how to construct the formula for $I'$.
I managed to get the value for $I_c$ using Thevenin and Norton ...
4
votes
2answers
47 views
Equivalent RC circuit to a RRC circuit?
I'm in doubt about a situation that I've seen sometimes: imagine we have a resistor in parallel with a resistor and a capacitor in series. Since I don't know how to generate figures of circuits to ...
-2
votes
0answers
20 views
Circuits using generators and cells and capacitors [closed]
This question was in a science worksheet we had, the description read as follows:
Tim has designed a generator that uses wind power and provides 9V. He decides to design a circuit using diodes ...
0
votes
2answers
34 views
Voltmeter forming a closed circuit
A battery is connected to a 10Ω resistor as shown in Figure 2. The emf (electromotive force) of the battery is 6.0 V.
When the switch is open the voltmeter reads 6.0 V and when it is closed it ...
0
votes
0answers
27 views
Differential BJT Amplifier [closed]
I am trying to solve this assignment
Consider this schematic (the BJT's are in the effective area, with
$\beta=200$ so as to $i_e\approx i_c$).
Define the common and differential gains, ...
-2
votes
4answers
143 views
Resistors in Parallel
From my book:
"A length of wire is cut into five equal pieces. The five pieces are then connected in parallel, with the resulting resistance being 2.00 Ω. What was the resistance of the ...
1
vote
3answers
90 views
Capacitor Charging and Discharging when connected to the ground
When we charge a capacitor using a battery and then remove the battery, the plates of capacitor becomes charged. One holds positive charge and the other one gets equal negative charge. o. k. ?
Now ...
2
votes
1answer
65 views
How we approach RLC circult from RLGC model?
In the text, it introduces a practical model to investigate a transmission line (like BNC cable), it considers the transmission line has resistive $R$, inductance $L$, conductance $G$ and capacitance ...
0
votes
2answers
50 views
Impedance of a circuit
I am trying the following problem. A resistor with $295\Omega$ and an inductor are connected in series across an AC source that has voltage amplitude of $550V$. The rate at which electrical energy is ...
0
votes
3answers
62 views
Voltage of open circuit
A battery with emf $\varepsilon$ and internal resistance $r$ is connected
with a resistor $R$ in the following open circuit. What is the voltage $V_{ab}=V_a-V_b$?
The answer is $- ...
-1
votes
1answer
81 views
Differentiating a sinusoid [closed]
http://i.stack.imgur.com/ndLgm.png
I don't see the how the author derived that $\frac { dv }{ dt } \leftrightarrow\overrightarrow { V } j\omega$.
3
votes
2answers
88 views
How can a circuit function with two negative battery terminals facing each other?
Here is a drawing of the circuit that is confusing me:
I don't quite understand how batteries work in this diagram. If a battery has a negative and positive terminal, there must be a barrier ...
0
votes
1answer
65 views
Is this series or parallel? [closed]
How do you find I? and please explain which resistors are in parallel and which are in series? ("M" and ">" are resistors)
...
0
votes
0answers
31 views
The heat dissipated in the resistance in a C-R circuit [closed]
If an uncharged capacitor (of capacitance $C$) is charged by connecting it with an ideal battery and a resistance R (The capacitor and resistor are in series combination ), then the heat generated in ...
0
votes
0answers
30 views
Alternating Current Circuits? [closed]
A 10.0 $\Omega$ resistor, a 12.0 µF capacitor, and a 17.0-mH inductor are connected in At what frequency is the current a maximum?
at resonant frequency the current is max:
$X_L = X_C $
...
0
votes
0answers
29 views
half wave rectification [closed]
A.C of frequency 50 Hz was passed through a diode. The electricity thus obtained was used
to glow an led. Is there any peculiarity in the light from the LED? (1)
(b) If the glowing LED is whirled ...
1
vote
1answer
97 views
Am I properly identifying the resistor terminal voltage?
The frequency applied to a circuit of voltage 120 V with a real coil and a resistor has a value of 50 Hz. The resistance of the resistor is 10 $\Omega$. The voltage at the resistor terminals ...
0
votes
0answers
52 views
What is the value of the equivalent resistance? [closed]
Can anyone tell me the value of the equivalent resistance for resistors R7, R8 and R9 in the following image?
Circuit -> { http://www.mediafire.com/view/?ktct310wyvezf2x# }
1
vote
6answers
637 views
Parallel circuits - Overall resistance decreases with additional resistor [closed]
Let's say that there is a parallel circuit with two identical resistors in parallel with each other. If a third resistor, identical to the other two, is added in parallel with the first two, the ...
0
votes
1answer
486 views
Relationship between resistance and voltage drop
In a series or parallel circuit, if two bulbs have the same resistance, do they have the same voltage drops? The problem I am asking about is below. Do A, B, and C have the same voltage drops since ...
0
votes
1answer
92 views
a metal bar on a pair of conducting rails that carries a current
This is a homework question, and I solved it already, but something bugs me. So the problem is stated as following:
A metal bar of mass M sits on a pair of long horizontal conducting rails separated ...
0
votes
1answer
106 views
Cable TV version of infinite ladder network [closed]
This is a problem in a college physics textbook, and its bugging me that I can't get it.
The figure shows a circuit model for the transmission of an electrical signal, such as cable TV, to a large ...
0
votes
1answer
74 views
Weird circuitry problem [closed]
I should note that I am asking these questions on behalf of a friend who claims to be too busy. Anyway here is a circuitry problem:
Why is C the correct answer?
0
votes
4answers
137 views
Why is there a potential difference?
The question then asks for the potential difference between $X$ and $Y$, which is claimed to be $3.6\text{ volts}%$.
Why would there be a potential difference in this case? If I connect a lightbulb ...
1
vote
3answers
169 views
kirchhoff's law.Simple question [closed]
So far I calculated total resistance and it is 4.66 ohms and there is 12 volt voltage across them, what is the best way or HOW to calculate current for each resistor ?
0
votes
0answers
361 views
How to find the equivalent resistance for the following circuit? [closed]
How do you find the equivalent resistance for the above circuit, if current is entering via A and leaving via C? Can it be done by treating it like a wheatstone bridge?
3
votes
3answers
217 views
What is the current through the lamp?
We have the following circuit:
A neon lamp and a inductor are connected in parallel to a battery of 1.5 $V$. The inductor has a 1000 loops, a length of $5.0 cm$, an area of $12cm^2$ and a ...
0
votes
1answer
153 views
How do I solve the current of this resistor using Maxwell's Current Theorem?
I've been trying to solve this using the method the prof. taught us, and I happen to know the answer but I can't reach it no matter how many times I've tried. The circuit in question is below:
I am ...
1
vote
0answers
89 views
Braess's Paradox in Electrical Circuits
According to this and other similar papers, http://www.nature.com/nature/journal/v352/n6337/abs/352699a0.html, adding a current-carrying path can increase the voltage drop across a circuit. What is ...
0
votes
3answers
542 views
Solving a rather unusual (diagonal) circuit
I have problems solving an electric circuit. I need to find the red drawn "I" (Current). However the way the electric circuit is drawn strikes me. I have very basic knowledge of physics and my skills ...
2
votes
1answer
208 views
Solving a circuit with Kirchoff/Ohms Law
Good evening,
I haven't had physics since year 7 and now I need to use elementary things in university. Since I lack a lot of basics I am now trying my best to fill these holes. Currently I am stuck ...
0
votes
1answer
92 views
What is the electric current $I_{12}$ and voltage $U_{12}$ in following electric circuit? [closed]
What is the electric current $I_{12}$ and voltage $U_{12}$ in following electric circuit? $I_{12}$ and $U_{12}$ are between points 1 and 2.
.
I have used this in constructing this electric circuit ...
3
votes
2answers
169 views
Instantaneous current after battery unplugged in RL circuit?
I've been racking my brain over this, and I can't find any clues in my textbook as to how to approach it.
I have the following circuit:
My goal is to find R such that, right after the switch is ...
1
vote
3answers
2k views
Finding current using EMF & internal resistance
What exactly is the difference between internal resistance and resistance?
This came up in the context of a homework problem I have been given:
The circuit shown in the figure contains two ...
1
vote
1answer
212 views
Imaginary voltage in simple RC circuit
As a homework assignment, we have to find $U_a(\omega)$, that is the voltage that drops over the right resistor in relation to the frequency $\omega$ of the input AC voltage $U_e$.
For the two ...
0
votes
3answers
438 views
Parallel or series connection?
Are C1, C2 and C3 connected in parallel, or C2, C3 in parallel and C1 in series with C23?
Btw it appeared as a question in the basic physics Albanian A-levels yesterday. You had to find the ...
2
votes
1answer
189 views
Power dissipated in resistor
Suppose one has a circuit consisting of an inductor $L$ and resistor $R$ in series where $L$ and $R$ are known, passes an alternating voltage of frequency $\omega$ through it and that one wishes to ...
0
votes
2answers
91 views
Does using batteries in a series raise the overall Wh's of the batteries used? Why/Why Not?
If one has 2 batteries of 6 Volts each with 500 mAh each, then separately the batteries should provide 6 Volts * 500 mAh = 3 Wh each or 6 Wh total. However would it be the case that if someone where ...
1
vote
1answer
74 views
Measure the voltage of a resistor without error
We have a simple circuit given, a resistor $R_x$ and a fixed current source with $I = 50 \, \mathrm{\mu A}$. Now over the resistor there is a currentmeter which has an internal resistance. In any case ...
-1
votes
3answers
156 views
Lightbulbs in circuits. Why does the current go UP? [duplicate]
Possible Duplicate:
Why does the light bulb's brightness decrease?
So I have a circuit in the picture with three resistors.
If I were to remove/disconnect $R_2$ from the circuit, ...
1
vote
2answers
397 views
Why does the light bulb's brightness decrease?
The book said that the brightness of R1 would increase and R2 would decrease. I don't understand this at all.
Why does adding a wire from b to c change anything to R1?
Shouldn't charge still flow ...
1
vote
1answer
102 views
Electric circuit. Slight problem with the sign on voltages
Translation first!
The figure shows an electric circuit.
a) Use Kirchhoffs 2.law on the part-circuit abed and show that $I_3$ = 0,50A.
b) Explain that $I_2 + I_5 = 2,0A$. Use Kirchhoffs 2.law on the ...
-1
votes
3answers
210 views
What's the right way to calculate charge on a capacitor?
How much charge is on each plate of a 4.00-F capacitor
when it is connected to a 12.0-V battery?
I said 2.4 x 10^-5 C because there are two plates of a parallel plate capacitor. But the key said only ...
-1
votes
2answers
2k views
How do I calculate output voltage from a given supply voltage and resistance?
I have searched everywhere but I can't seem to find out how I can calculate the output voltage (or voltage over a component) from the resistance of a resistor (or other component) and the supply ...
1
vote
1answer
882 views
RC Circuit , Calculate Time Constant
Given this diagram:
With S1 switch closed and S2 switch left open, I am trying to find the time constant
Relevant equations
I know τ = RC for a basic circuit, but how would you calculate it for a ...
0
votes
1answer
926 views
Battery Calculations [closed]
I have been given the following statistics for a battery and I have been asked to find the
1) battery capacity in Wh
2) volumetric energy density in Wh/cm3
3) gravimetric energy density in Wh/kg.
...
1
vote
1answer
981 views
How to calculate the charge and the potential across a charged capacitor charging an uncharged capacitor?
Initially, there is a single capacitor $A$ attached to a power source that charges it to a certain voltage $V$. Once it is charged, it is instantaneously removed and placed in a circuit with an ...
0
votes
1answer
873 views
As ISA Practical - Resistors in Parallel [duplicate]
Possible Duplicate:
Current against the inverse of resistance graph, I = V/R +c
How would you set up a circuit with a fixed resistor in parallel with a variable one. We are told to measure ...
0
votes
2answers
979 views
Internal resistance V=IR circuit question [closed]
I don't know how to resolve this problem.
A complete circuit consists of a 18,0 V battery (internal resistance r) and a resistor R. The terminal voltage of the circuit is 15,8 V and the current is ...
