-4
votes
0answers
19 views

Capacitance of air capacitor [on hold]

Hi I'm currently working on the following question (image below), any help is much appreciated!
-2
votes
0answers
33 views

Electricity Problem [on hold]

A power Station Is Connected To A Factory 2.5 km Away By Two Wires the potential difference between the terminals of the wires at the station is 240v and that for the other terminals at the factory ...
-4
votes
0answers
48 views

Electricity Conductor [on hold]

Which is the good conductor of electricity among these? Tap water. Sea water. Please send answers today itself. Its very urgent.
0
votes
1answer
56 views

Simple Parallel Electric Circuit [closed]

Ammeter (A1) and voltmeter (V) in series have parallel connection to another ammeter (A2). Currents in A1 and A2 are respectively 0.2 and 1.7 amp. Voltmeter's voltage is 6 volts. How should I find ...
2
votes
1answer
62 views

Would it really require 44 car batteries to heat my pool? [closed]

After doing some research and math, I 'discovered' that it would take 44 (give or take 20%) car batteries to heat 1,000 gallon pool by 10 degrees. Is this right or am I missing something? It seems a ...
1
vote
2answers
95 views

Electric potential of spherical water droplet [closed]

I'm trying to answer the following: 1000 spherical water droplets, each of radius $r$ and each carrying a charge $q$, coalesce to form a single bigger spherical drop. If $v$ is the electric ...
1
vote
1answer
124 views

Electric field generated by a point charge moving at the speed of light

As you see, this is the electric field generated by a point charge moving at constant speed v. I know that when $v$ -> 0, $E$ is just the Coloumb Law. But how do you interpret $E$ when $v$ -> $c$ ? ...
0
votes
1answer
155 views

Boundary conditions of this problem

We have A point charge, a homogeneously charged insulator with total charge $Q''$ which is a ball with radius $R$, a conducting metal ball with charge $Q'$, radius $R$ and a grounded metal (no ...
-3
votes
2answers
53 views

Other units of resistance [closed]

Resistance is $\frac{V}{I}$, and we get the unit $\Omega$. Another unit is $\frac{W}{A^2}$. How do you derive that unit?
0
votes
2answers
70 views

combination of cells

There are m*n identical cells of emf E and internal resistance r connected in parallel rows. This combination of cells is connected across an external resistance R. For what arrangement of the ...
1
vote
1answer
45 views

Battery Capacity vs. Battery draw

Pardon my ignorance but I just can seem to find an Answer to my question and I hope that you can help me. What is the equation for calculating how long a Lithium Battery can supply a device? For ...
1
vote
1answer
52 views

Circuits and Power

"The diagram below represents a simple circuit composed of 5 identical light bulbs and 2 flashlight batteries. Which bulb (or bulbs) would you expect to be the brightest? a) V only b) V and W ...
0
votes
2answers
60 views

Finding the voltage of an inductor in a RL series circuit [closed]

Here is the solution: This assigned question is an odd one since it doesn't seem to have anything to do with phasors which is the chapter I am currently studying. I know that that the phase ...
0
votes
3answers
64 views

electric current in parallel circuit [closed]

If I have a parallel circuit with two resistors ($R_1=48 \Omega$ and $R_2=16 \Omega$) - and $R_1$ has a $0.1 A$ current running through, is it possible to calculate the current through $R_2$ without ...
1
vote
3answers
96 views

Current through two inductors after a long time

I'm having trouble with visualizing the following problem, which is asking me for the final, steady current in both inductors $L_{1}$ and $L_{2}$. I was thinking that after a long time, essentially ...
0
votes
2answers
111 views

Photoelectric effect: current vs wavelength

In an experiment where the type of metal,intensity of light and potential difference across a battery is kept constant at 2V the results show that an increase in wavelength, obviously in turn ...
1
vote
1answer
65 views

Work-Energy-Power Relations

A wind-powered generator converts wind energy into electrical energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. ...
0
votes
0answers
50 views

Kirchoff Loop and current

The pic of the circuit/problem: I got the problem right, but i want to make sure my reasoning is correct for the current left of the 2.1 V battery. Its the same current as $I_1$ because the ...
1
vote
0answers
63 views

Different phase in capacitively coupled RLC circuits

I was trying to work with some data for a lab report I'm writing about capacitively coupled RLC circuits. The setup is pretty simple and looks like that: Where $C^{'}$ is the coupling capacitance. ...
-2
votes
2answers
69 views

Is R1 R2 and R3 parallel? [closed]

or R2 and R3 are parallel then they are in series with R1?
1
vote
0answers
85 views

Electric field produced by a charged ring

I have a question I couldn't find an answer for anywhere. There is a ring of radius $R$ which is charged uniformly with linear density $\lambda$, and I have to find the electric field on any point of ...
1
vote
0answers
68 views

Finding the induced EMF on a bar - Faraday's law

I have a couple of questions about the following problem: A conducting bar of length L moves with velocity v, in a rectangular region with a uniform and stationary magnetic field B_1. Near the bar, ...
-1
votes
1answer
24 views

Computing power based on weighted averages [closed]

I'm struggling to understand the reason why I'm getting different results with two apparently similar ways to compute the power consumption (over multiple time intervals) of an electrical circuit. ...
4
votes
1answer
74 views

How to get a function for the voltage across a capacitor connected to an AC voltage source? [closed]

I am looking for the way of obtaining a solution for $V_{c}$ ,as a function of $t$ depending of $\omega$, of the following differential equation related to an electrical circuit involving a low-pass ...
0
votes
2answers
235 views

How do I combine three resistors which are in parallel with each other?

For this circuit (a and b are connected by a battery), Will I be able to find the total resistance of the circuit by adding resistors that are in series and combining resistors that are in ...
-1
votes
2answers
2k views

Solving circuits using kirchhoff's laws and elimination method ( not any matrix method) [closed]

I need to solve this problem as part of my review in college physics. The task is to find the value of 5 branch currents using Kirchhoff's laws and elimination method (or maybe called elimination by ...
-2
votes
1answer
41 views

Using a lemon's energy [closed]

Some simple exercises i need some confirmations on. Let's say a lemon has U = 1V and an average current of 0.1mA for about an hour. Q1. How much lemons do you need to light a 100W bulb. Is the ...
0
votes
0answers
40 views

Capacitance in a capacitor

This here is a question that I just don't know what to do with. I don't know what I'm doing wrong. "A plate capacitor consists of two plates with area 2.5 cm$^2$ at a distance of 1.6 mm from each ...
1
vote
2answers
114 views

Total Resistance in a Tetrahedal loop [closed]

Imagine if I placed resistors of 1 ohm each in shape of tertahedal. What would the total resistance be between A and D? I can't find any website that gives me a good explaination.
0
votes
2answers
41 views

Capacitance and energy

So I've been reading about capacitance (Specifically in capacitors) and I'm wondering if this reasoning is sound, and why/why not: C = Q/U U = Q/C We also know that: U = E/Q So: E/Q = Q/C Q^2 = ...
-1
votes
2answers
80 views

How to convert RL Circuits? [closed]

How do we convert a parallel RL circuit into its equivalent series RL circuit ?
2
votes
3answers
187 views

How to calculate Standing Waves in Electrical Cables?

I have a 20 metre Coaxial Cable. I send digital signals down the cable ranging from 5 KHz to 50 KHz. I have noticed a pattern in the noise ratio, an oscillating wave. I predict this is to do with ...
0
votes
1answer
49 views

Applying more current? [closed]

An electric motor draws 20 Amps, when at maximum load of x. Can that value of current be applied even if the load was ten times less than x from a certain power source?
0
votes
1answer
87 views

Is there another way besides $V = k\int dq/r$ to find potential?

Suppose that the charge distribution $q(r)$ in the radial $r$-direction in a thin hollow disc of inner radius $a$ and outer radius $b$ is given by the power-law equation: $$q(r) = Q_0 \left[1 ...
0
votes
5answers
670 views

How would I explain Ohm's Law in terms of Electrical Fields and Force?

In terms of current, resistance, and voltage, it's easy: Ohm's Law is the relationship between current, voltage, and resistance of a circuit. Boom, simple as that. How could I put this in terms of $E$ ...
0
votes
2answers
55 views

Yearly onshore wind turbine energy production [closed]

I am trying to work out the yearly energy production of an onshore Siemens SWT-3.0-101, hub height 94m, total height 144,5. Here is the power curve at each wind speed level worked out through a ...
0
votes
1answer
259 views

Use kirchhoff's second law to deduce the resistance R of the resistor [closed]

Using what I learned so far, i constructed an equation like this: $$30V=(I_{1}\times 20\Omega)+10V+(0.2A\times 10\Omega)+(I _{3}\times 10\Omega)+(0.5A\times R)$$ Which is clearly not solvable on ...
0
votes
1answer
103 views

E&M question in example in my book [closed]

So I still not sure how to apply like Right-hand rule (RHR) in this setup in problem like the one in the following so I tried to do RHR in order to get the direction but it didn't work out. This is an ...
0
votes
1answer
56 views

Tungsten Wire Heat discipation

Background Information: I'm doing an experiment in which I place a bare tungsten wire in to various liqids, to measure a coefficient $\alpha $ in the equation $$ Power Dissipated = \alpha * \Delta T ...
2
votes
1answer
89 views

Calculate required voltage in mixed circuits [closed]

Q: Calculate the voltage that V1 has to provide Given: The following circuit. The voltage through LAMP1 is 5.0V. A (U,I) chart (not shown). LAMP1 and LAMP2 are identical, non-ohmic lightbulbs. ...
1
vote
0answers
40 views

Lorentzforce and righthand rule [closed]

Figure 1: A spool is hung on a spring. A part of the coil hangs in front of a homogeneous magnetic field. The coil is incorporated in an electrical circuit. See Figure 1. the coil ...
4
votes
1answer
717 views

Electric Field from Dielectric Shell

This is a question taken from a past E&M exam A thick spherical shell (inner radius $R_1$ and outer radius $R_2$) is made of a dielectric material with a "frozen in" polarization ...
0
votes
1answer
122 views

Find current in a nontrivial circuit

Let us assume that we have this circuit: We know that: $$I_1 = I_2 + I_3$$ $$I_1R_1 + I_3R_3 = V$$ $$I_1R_1 + I_2R_2 + \dfrac{q_c}{C_1} = V$$ Therefore we can write: $$I_1 = k_1 - k_2*q_c$$ ...
1
vote
1answer
86 views

Resistances in a circular loop

I have no idea what formula I'm supposed to use.I just want to know the concept that would allow me to get the answer. I know basic concepts of electricity like charge, currents, etc., but as far ...
1
vote
1answer
147 views

Question about superconductivity

A long cylinder of radius $R$ is made from two different material. Its radius $r<r_0$ $(r_0<R)$ part is a material with superconducting transition temperature $T_1$, and its $r_0<r<R$ ...
2
votes
0answers
230 views

Calculating Electric Field from a Potential Difference w/o Charge

So here is my homework question: Two long cylindrical shells of metal (radii $r_1$ and $r_2$, $r_2 > r_1$) are arranged coaxially. The plates are maintained at the potential difference ...
2
votes
2answers
127 views

Strange electrical circuit

This is a question I would like to have an explanation with: It's in this PDF, question 9. In that circuit, if switch 1 is closed, bulb A burns normally. If 2 is closed as well, do other lamps ...
-3
votes
1answer
80 views

combination of 5 identical capacitors [closed]

Given 5 identical capacitors, each EMF. Draw the proper combination of all these 5 capacitors.. 1.) 2.5 2.) 4.17 I really do not know how to solve this thing and if anyone of you knows the title of ...
1
vote
1answer
1k views

Where does the energy of a light bulb come from?

Where does the energy of a light bulb come from? Is it from the coil of wire, magnet in the generator, mechanical input to the generator or plug where the generator is connected to the wall?
0
votes
0answers
88 views

Why does an armature of a generator rotate?

Why does an armature of a generator rotate? a) like poles repel b) unlike poles attract c) current flows up d) an outside force turns it I am thinking that (d) is the correct answer but ...