The electric-circuits tag has no wiki summary.
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Experimental study of the Photoelectric effect [duplicate]
As I was reading about the experimental arrangement for photoelectric effect, I saw a diagram that puzzled my knowledge of electrodes. I found that in the experimental setup the cathode of the ...
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1answer
31 views
Circuit elements classification
I want to understand from theoretical point of view the structure of electric circuits. I don't mean Ohm's law or the Law of induction...
E.g. there are resistors $R$, capacities $C$, inductors $L$ ...
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2answers
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Why two connected 1.5 volt battery become 3 volt
Why two connected 1.5 volt battery become 3 volt?
If one battery plus side is connect to minus side of another battery, there should be a current flow between them until no free charge move anymore, ...
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EMP gun practical issue [closed]
I tried to build an EMP(electro magnetic pulse) device. I read about it on the internet and I found some possible circuits. For build the device I used a diode, an high voltage capacitor, a swich, a ...
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0answers
32 views
Completing a circuit, how is the necessary voltage determined? [migrated]
When you have some device, like a TV, why is there a necessary Voltage-or current for that matter. Whenever I see circuits, it always says to find the current from the voltage and resistance given, so ...
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27 views
How to size an electromagnet
How can I size an electromagnet? For example if I would to attract a mass of $x$ kg what are the calculations that I must do to size the ferromagnetic core and of course the solenoid? And thus, how ...
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2answers
70 views
Why do current-carrying wires heat up?
Obviously wires heat up too, but why do they heat up? And for the same reason, why do we get electrical burns?
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5answers
206 views
Why are wires in simple circuits approximated as equipotentials?
I just answered this question:
Voltage in a circuit
by asserting that any two points joined only by a wire, but no other circuit elements, are at the same value of the electric potential. It is, of ...
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2answers
80 views
Voltage in a circuit
Suppose I have a following circuit:
I do not understand, why the potential difference between the points $c$ and $d$ is equal to the potential difference between the points $b$ and $a$? That is, ...
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Birds on telephone wires, different voltages [duplicate]
I know there have been questions about birds on telephone wires before- but isn't each foot at a slightly different voltage? Nothing is actually equipotential is it?
So why don't birds feel a shock?
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2answers
148 views
$V=IR$, isn't it missing something?
So I know that $V=IR$ works for circuits, but for the case of an arc-before the arc jumps, there is a potential difference, but no current, but there isn't infinite resistance is there?
I don't ...
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21 views
Why does wet skin offer less resistance?
I know that water with salts is a good conductor-However wetting a hand only adds water to a not very conductive surface. How does water actually reduce the resistance of skin? The way I am seeing it ...
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0answers
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How to prove this fundamental relationship $ b=\ell+n-1$? [migrated]
How to prove this fundamental relationship?
In a network or circuit, number of loop, nodes and branches has to satisfy the following fundamental relationship:
$$ b=\ell+n-1,$$
...
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0answers
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Why is zener current preferred to be more than load current in a voltage regulator? [migrated]
In a simple Zener Voltage Regulator, such as this
Why should current passing through the zener diode(zener current) be more than the current passing through the load(load current)?
or
No such ...
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2answers
54 views
Thevenin equivalent of a circuit
Ok so I can't post the image of my question and my attempt at it,
so I would like to ask, if anyone knows the steps to simplifying a circuit with dependent current sources, independent voltage ...
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2answers
54 views
How does symmetry allow a rapid determination of the current between $A$ and $B$?
The following was originally given to me as a homework question at
my physics 2 course:
Consider the following circuit
The difference of potentials between the point $V_{1}$and the ...
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1answer
30 views
Would the empirical behavior of a simple circuit match my model of it?
I have a practical problem in E&M which has baffled me and and my electrician. The copper water pipes in my house are carrying a current of small potential (~1V) AC current. Here is my ...
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0answers
29 views
About electric current analogy
my teacher gave me this analogy to the electric current , the wire is like a pearl necklace where the pearls can move, the current or the movement of electrons is like putting your fingers between 2 ...
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1answer
41 views
Total current of two sources in series? [closed]
Here is a question that a friend asked me. He had to an experiment in school and do some calculations afterwards. Those calculations require maximal current that the DC source can produce. He has ...
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2answers
85 views
How to find $\tau$ in this circuit?
1)
2)
I know, that
$$
τ = \frac{L}{R}
$$
but what is $R$ in this formula? It seems to be the total resistance, but how to find it in 1) and 2)?
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1answer
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Capacitor and Voltage without $R$ [closed]
I have a problem about this question.
$C = 20 \mu F$
$v_s(t) = 0 \text{ for } t < 0$
$v_s(t)= 104t^2 V,\text{ for } 0 < t <0.1s$
$v_s(t) = 100 V,\text{ for } t >0.1s$
(a) Find ...
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1answer
42 views
Power in hydraulic analogy
In hydraulic analogy one compares electrical circuits with water circuits. For the electric case the formula $P = U \cdot I$ for the electric power holds. The analogous formula for water flow would ...
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1answer
43 views
Circuit Loop Law Doubt
In a circuit with a solenoid/inductor and a resistor and a battery .
Books say that $\Sigma \Delta V=0$ around a closed loop . That means work done by electrostatic field per unit charge is $0$ ...
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0answers
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Capacitance of stable circuit [closed]
A circuit contains two resistors ($10\: \Omega$ and $20\: \Omega$) and
two capacitors ($12\: \mathrm{\mu F}$ and $6\: \mathrm{\mu F}$)
connected to a $6\: \mathrm{V}$ battery, as shown in the ...
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1answer
104 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 ...
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1answer
43 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 ...
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0answers
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Current distribution in inductors
I have been trying to figure out how current is distributed in a circuit with multiple inductors. I could not find any specific info regarding the topic but I guess it is similar to the case with ...
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2answers
79 views
What happens when non-equal voltages are put in parallel? [duplicate]
If two batteries, say 2 volts and 5 volts, are connected in parallel, are there any problems? The higher voltage will then want to flow out, but also towards the lower 2 volt battery end, right?
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1answer
23 views
Doubt on the analysis of $RC$ circuit
I'm studying $RC$ circuits and I'm in doubt on how to deal with one kind of situation. Well, first when we have simply a circuit with just one resistor and one capacitor in series, or a circuit that ...
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2answers
58 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 ...
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0answers
30 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 ...
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2answers
52 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 ...
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2answers
79 views
Different batteries connected in parallel
If we have 2 batteries one of emf x and the other is of emf y and we connect them in series we get an effective emf of x+y.
But what if we connect them in parallel, how to calculate the emf now?
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1answer
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How does my hand amplify an FM radio signal?
I have a gizmo that broadcasts an FM radio signal from my phone's headphone socket to my car's radio antenna.
Sometimes, there's another station on the same frequency with a stronger signal and my ...
4
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3answers
288 views
Why don't electric workers get electrocuted when only touching one wire? [duplicate]
I know that when electricians work on the poles on the streets, if they only touch one wire at a time they will be fine. However, from my understanding, the negative wire is connected to a large ...
2
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1answer
107 views
Experiment to find Ammeter Resistance [closed]
I've been studying experimental electrodynamics and I needed to describe an experiment to find the resistance of an ammeter if I just have the ammeter together with one voltmeter and a protection ...
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0answers
28 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, ...
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4answers
158 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 ...
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4answers
140 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 ...
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43 views
reflected wave in the transmission line
I am reading a book about the telegraph equations on the transmission line, which is illustrated as follow
where the input impedance is $Z_0$ and the impedance of the load is $Z_L$, we setup the ...
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0answers
58 views
Capacitors discharging in series [duplicate]
If you connect positive plate of a charged capacitor to ground, it doesn't get discharged. Now consider $4$ capacitors of equal capacitance connected in series to a $10\, \mathrm{V}$ battery. Connect ...
2
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1answer
95 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 ...
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1answer
42 views
Finding the Steady State Charges
Here the problem states to find the steady state charges on the condensers.<<<<
According to me the charges on second at steady must be ...
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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 ...
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3answers
81 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 $- ...
0
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1answer
105 views
measuring electromagnetic induction
There is a famous law which says that a potential difference is produced across a conductor when it is exposed to a varying MF. But, how do you measure it to prove? It is quite practical.
...
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3answers
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When does Thevenin's theorem not apply (modelling a power source with a ohmic internal resistance)
Most physics text books say that a power source can be modelled as an EMF with a internal resistance. This is also know as Thevenin's theorem or Norton's theorem. However I have read in some sources ...
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1answer
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Confused on Calculating Resistance Distance Matrix
I am trying to create a computer program to compute the equivalent resistance over any points on any rectangular set of resistors (all with a resistance of 1 ohm). It seems that the resistance ...
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1answer
82 views
Differentiating a sinusoid [closed]
http://i.stack.imgur.com/ndLgm.png
I don't see the how the author derived that $\frac { dv }{ dt } \leftrightarrow\overrightarrow { V } j\omega$.
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2answers
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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 ...
