Tagged Questions
-2
votes
1answer
32 views
Resistance of a copper wire [closed]
Resistance of a copper wire is 20ohm. If the diameter of the wire is 5mm and length 1ohm. Find the resistivity of the copper.
0
votes
1answer
36 views
The potentiality of the electric field
Could you, please, explain me using just words why electric the field is potentially? I know the proof using integral: $A = \int_{12}q\overrightarrow{E}\overrightarrow{dr} = ...
0
votes
2answers
31 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 ...
1
vote
3answers
78 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 ...
0
votes
3answers
61 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
votes
0answers
44 views
The electrical field of a conductive sphere containing a charge - gounded vs not grounded
Let's suppose we have a sphere but unlike theoretical ones it'll has have some thickness say $\Delta r$ and inner radius $R$. What I was wondering about is how will it behave if we place some charge ...
0
votes
1answer
79 views
How to design a AC/DC generator and motor? [closed]
Through electrodynamics mechanics learning, it is possible to design a simple and elegant design for the following four machines:
1. AC generator
2. AC motor
3. DC generator
4. DC motor
I have some ...
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
45 views
Really Confused about Drift Velocity [closed]
I'm having a really hard time understanding drift velocity
A current of 10.0A is carried by a copper wire of diameter 1mm. If the density of the conduction electrons is 8.47 x 102m-3, how long does ...
0
votes
1answer
104 views
Does the electric field inside a sphere change if point charge isn't in center?
As i understood , if you have a point charge in the center of a hollow conducting sphere then the electric field inside it, is zero because the charge distribution is spherically symmetric.
But ...
1
vote
1answer
96 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
50 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# }
0
votes
0answers
41 views
AC source and the capacitor [closed]
An AC circuit is connected to a capacitor. Will the rms current increase, decrease or remain constant if the dielectric slab is inserted into the capacitor?
2
votes
1answer
76 views
What exactly causes an increase in resistivity?
Explain in terms of charge carriers why the resistance of copper is less than that of CuSO4 solution, which is less than that of hydrogen gas
This is the question directly asked for homework, and ...
1
vote
2answers
695 views
Physical interpretation of y-intercept in a Current vs Voltage graph
So I collected current and voltage data from a simple circuit with a power source and a resistor, using a multimeter. I created a graph for this data using excel and got the y-intercept (which is ...
0
votes
4answers
129 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
1answer
123 views
Finding the Electric Field (and other information, besides)
The problem I am working on is:
Two parallel plates having charges of equal magnitude but opposite sign are separated by 29.0 cm. Each plate has a surface charge density of 33.0 nC/m2. A proton is ...
0
votes
0answers
351 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?
0
votes
1answer
339 views
Finding Current and Voltage through resistors given overall voltage and resistor values
Given a setup like:
Is it possible to find current and voltage through each resistors given resistor values and overall voltage (battery voltage I suppose).
I think $$I_0=I_A=\frac{\Delta ...
0
votes
0answers
75 views
short question - charge [closed]
Four identical metal spheres have charges of q1=-8.0 micro C,q2 =-2.0 micro C, q3 =+5.0 micro C, and q4 =+12.0 micro C.
Three of the spheres are brought together so they touch, and then they are ...
1
vote
1answer
109 views
Transformators (primary and secondary windings)
Consider the following problem:
Robby wants to put a light in the shed so he puts a cable between his house and the shed. In the cable there are 2 wires with a combined resistance of $0,92 \space ...
0
votes
1answer
131 views
Finding and plotting the current graph from a voltage graph (piecewise function)
Problem description:
My attempt at making the piecewise function:
Then, in order to find i(t), I took the derivative of 80x/3 and -80x/3, with respect to x, and multiplied C. Obviously, I'm left ...
1
vote
0answers
87 views
Braess's Paradox in Electrical Circuits
According to this and other similar papers, http://www.nature.com/nature/journal/v352/n6337/abs/352699a0.html, adding a current-carrying path can increase the voltage drop across a circuit. What is ...
1
vote
2answers
96 views
Why doesn't a neon sign seem that hot?
I heard that neon signs contain plasma, why aren't they hot?
is it because the electrons and ions do not hit the lamp's wall?
Is it because it is non thermal plasma and electrons and ions are not in ...
0
votes
1answer
175 views
Capacitance and Light Bulb And Dielectric Slab [closed]
An electric lamp having coil of negligible inductance connected in series with a
capacitor and an AC source is glowing with certain brightness. How does the
brightness of the lamp change on reducing ...
1
vote
2answers
144 views
Is it really to solve problem below by using, in the main, Gauss law?
There is an infinite cylinder surface which uniformly charged along and has a surface charge density, which can be represented as
$$
\sigma = \sigma_{0}cos(\varphi ),
$$
where $\varphi$ - polar angle ...
1
vote
1answer
203 views
Solving by using Gauss law
Task: find the vector $ \mathbf E $ in the center of the sphere with radius $R$, which has charge volume distribution $\rho , \rho = (\mathbf a \cdot \mathbf r ), \mathbf a = \operatorname{const}, ...
0
votes
3answers
455 views
When I connect two charged capacitors side by side, what will be the voltage across them?
Say, I have two charged capacitors, one 3mF and one 2mF. The voltage across them are 20V and 30V respectively. Now if I connect the two capacitors side by side as shown below, what will be the voltage ...
0
votes
3answers
424 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 ...
0
votes
2answers
89 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
130 views
Toroid with variable current and Ampere's Law
Say you have a current $I(t)$ (notice the time dependence) flowing through a Toroid with $N$ total loops and all the usual approximations: $(b-a) \ll r,\; B=0$ outside.
You are asked to calculate ...
0
votes
0answers
16 views
I want to charge 48V 108Ah battery from 48V 80Watt solar panel. Can anyone write that how much time will take this battery to fully charge? [duplicate]
Possible Duplicate:
Charging 12V 150Ah battery
I want to charge 48V 108Ah battery from 48V 80 Watt solar panel. Can anyone write that how much time will take this battery to fully charge?
0
votes
1answer
907 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.
...
0
votes
1answer
871 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
952 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 ...
0
votes
2answers
328 views
Does power from a resistor perform work or heat transfer?
Let's say I have a cylindrical piston filled with air and fitted with an electrical resistor. The resistor has a current going across it and a voltage for a certain amount of time. My system would be ...
1
vote
2answers
749 views
Measuring the Electromotive Force and Internal Resistance of a Battery?
Here is a problem that emerged some time ago:
We needed to measure the emf(electromotive force) and internal resistance of a car battery. The only instruments were voltmeter and ammeter.
...
1
vote
3answers
260 views
Problem with an electricity / thermodynamics assignment
I've been trying to figure this one out for a while on my own, so I'd like to ask for your help if you could offer some.
The task states:
A heater made out of a wire with a diameter $R = ...
0
votes
1answer
71 views
Resistance from voltage and charge [closed]
I'm sure this is pretty basic, but I'm not very good at electricity.
At both ends of a conductor we apply 12 volts. For one minute an electric charge of 72 C passes through the conductor. What is ...
2
votes
2answers
203 views
Small scale water power, how does water volume and hight convert into electric energy?
I was playing a little bit with the basic physics behind water power production but I can't get the numbers right.
Let's say that I put a windmill that pumps water into a watertank on the top of my ...
0
votes
2answers
5k views
Determine the point at which the electric field is equal to zero?
Two point charges, -2.5 micro coulombs and 6 micro coulombs, are separated by a distance of 1m (with the -2.5 charge on the left and 6 on the right).
What is the point where the electric field is ...
2
votes
4answers
792 views
Calculating current used by individual resistor?
I just recently finished a test on Physics, and when receiving my scores back I missed a question. Here's what it was if I can remember it correctly:
Three resistors (10.0, 15.0, and 6.00 ohms) ...
2
votes
2answers
528 views
Electric potential in a capacitor
Im a writing a school report regarding the electric energy and potential of a capacitor.
In short:
An experiment was carried out where we charged a capacitor, and then decharged it with an electric ...
0
votes
4answers
196 views
Calculating electric field
This problem is giving me a lot of problems. So $E=k*q/d^2$. We'd want to find the distance from q1 to P, which is .1 meters (not cm) using pythagorean thereom. So we know k, which is just $9x10^9$ ...
1
vote
2answers
1k views
Transfer function of an RLC circuit
I'm trying to simulate an RLC circuit using transfer function. Circuit is there: http://i.stack.imgur.com/MC8ME.png (I'm a new user therefore I cannot post images)
But I can, L.Motl...
Main ...
0
votes
2answers
529 views
Space state equation for RLC to calc voltage on resistor and capicitor [closed]
I have some task to do:
Please write equations in Simulink and
simulate the circuit elements
connected in series RLC (it was the
electrical!). Outputs of the system
should be voltage on ...
-5
votes
1answer
146 views
Amount of 2 amperage [closed]
I have 2 equation describing the alternating amperage i1 and i2. I need to get amount of these amperages.
My equations:
i1= 10 sin (ωt+30)
i2= 20 sin (ωt-50)
...
