What is Resistance: Definition and 1000 Discussions
The French Resistance (French: La Résistance) was a collection of French movements that fought against the Nazi German occupation of France and the collaborationist Vichy régime during the Second World War. Resistance cells were small groups of armed men and women (called the Maquis in rural areas) who, in addition to their guerrilla warfare activities, were also publishers of underground newspapers, providers of first-hand intelligence information, and maintainers of escape networks that helped Allied soldiers and airmen trapped behind enemy lines. The Resistance's men and women came from all economic levels and political leanings of French society, including émigrés, academics, students, aristocrats, conservative Roman Catholics (including priests and nuns), Protestants, Jews, Muslims, liberals, anarchists, and communists.
The French Resistance played a significant role in facilitating the Allies' rapid advance through France following the invasion of Normandy on 6 June 1944. The French Resistance provided military intelligence on the German defences known as the Atlantic Wall and on Wehrmacht deployments and orders of battle for the lesser-known invasion of Provence on 15 August. The Resistance also planned, coordinated, and executed sabotage acts on the Nazi electrical power grid, transport facilities, and telecommunications networks. The Resistance's work was politically and morally important to France both during the German occupation and decades that followed. It provided the country with an inspiring example of the patriotic fulfilment of a national imperative countering an existential threat to French nationhood. The actions of the Resistance stood in marked contrast to the collaborationism of the Vichy régime.After the Allied landings in Normandy and Provence, the paramilitary components of the Resistance were organized more formally, into a hierarchy of operational units known, collectively, as the French Forces of the Interior (FFI). Estimated at 100,000 fighters in June 1944, the FFI grew rapidly and reached approximately 400,000 by October. Although the amalgamation of the FFI was, in some cases, fraught with political difficulties, it was ultimately successful, and it allowed France to rebuild the fourth-largest army in the European theatre (1.2 million men) by VE Day in May 1945.
Homework Statement
An office worker uses an immersion heater to warm 250 g of water in a light, covered, insulated cup from 20 degrees C to 100 degrees C in 4 minutes. The heater is Nichrome resistance wire connected to 120V power supply. Assume wire is at 100 degree C during 4 minute time...
Homework Statement
In a simple RC circuit the current as a function of time behaves in the following manner:
I(5s) = 8.823
I(10s) = 7.788
I(20) = 6.065
I(30) = 4.724
I(40) = 3.679
I(50) = 2.865
I(60) = 2.231
I(70) = 1.738
I(80) = 1.353
I(90) = 1.054
I(100) = 0.821
I(110) = 0.639
Assuming...
For a school project, I need to know how much less wind resistance a round skyscraper will have compared to a standard rectangular one. You can assume the skyscraper will simply be a generic elliptical shape, somewhat similar to an egg. Answer doesn't have to be extremely specific, I just need...
Homework Statement
Ok, so I am attempting to solve a projectile motion problem involving air resistance that requires me to find the total x-distance the projectile traverses before landing again.
Given:
\\
m=0.7\text{kg}
\\
k=0.01 \frac{\text{kg}}{\text{m}}
\\
\theta=30 \degree
Homework...
I have a problem understanding the concept of potential difference. I get the picture of seeing it as a height difference for example (rock or water that would fall down) but what confuses me is that many times the order of elements in a circuit does not matter. To explain myself better: if I...
Homework Statement
Find the Thevenin's equivalent with respect to points A and B
Homework Equations
3. The Attempt at a Solution [/B]
The resistance i found to be
##R_t=(R_2+R_1)||R_3+R_4## and that is the correct expression but for the voltage source the book gives...
Homework Statement
This is the second problem from our test preparation cycle and i partially solved and understood it.
The circuit in the picture is in the state of switch being open (STATE 1: SWITCH OPEN). Calculate ##E1## so that the change in the electrical energy of the capacitor is...
Homework Statement
This is one of the problem i had had some help in solving but some things remain unclear to me and i will highlight them by posting the exact question in the brackets next to the line of solution so that you can see what bothers me. Hopefully you can help me better understand...
Homework Statement
I'm currently working on the "cavendish" experiment and wish to use/develop a method separate from the casus we've been provided. Now I've nicely calculated and derived everything I need to know, including all the corrections that have to be made for the mass of the rod, the...
Homework Statement
I am trying to develop simulation for a falling object subject to air resistance. Object is similar to Samara seed. object is considered to be under steady vertical descend.
know variable :
surface area of object (A)
weight of object (W)
cd: drag coefficient
object rotates...
Hi PhysicsForums,
Why would a parallel circuit(or in blood) decrease resistance?
Here is my thought experiment and where I got stuck:
Say from aorta to one arteriole, the resistance is super high on that flow(this big amount of flow is entering a tinier area), but add more arterioles and we...
Homework Statement
In the figure given what is the Thevenin resistance between the nodes of the capacitor??
Homework Equations
The Thevenin resistance is the open node resistance between two points.
The Attempt at a Solution
The way I see it, R2, Rf and R1 are in series and that combination...
Homework Statement
Determine the Thevenin and Norton equivalents at terminals a-b of the circuit in Fig. 4.125. The figure is uploaded.
Homework Equations
We know that the Thevenin resistance is the resistance between the terminals when the independent sources are turned off.
The Attempt at a...
Homework Statement
(##R_5=8\Omega##)
a) Calculate the current ##I_{g2}## so that the power of the generator ##I_{g1}## equals ##P_{ig1}=6.25W##
b) What is ##I## then?
Homework Equations
3. The Attempt at a Solution [/B]...
How is the constant used to measure resistance? I can't find a clear answer anywhere. The constant is h/e^2 but that doesn't really help in seeing how it is linked to resistance other than the units being the same in base units.
i connected one probe of digital mutimeter to the Earth terminal of domestic ac supply and held the other probe. it showed resistance of 1.8Mohm .
but when i touched that end (one i'd held) to the floor. it displays 1( beyond 200Mohm ). why so ? shouldn't resistance be lesser?doesnt any current...
Homework Statement
I understand part a, but not part B.
Homework EquationsThe Attempt at a Solution
For part b) the PD across the resistor is 2V, but we don't know the current so we can't calculate using ohm's law eqn.
And because the new resistor's resistance is unkown, how do we actually...
Homework Statement
I am asked to calculate the missing resistance(R5) when only given the voltage drop of of 14v across it
Homework Equations
current and divider rule
ohms law
The Attempt at a Solution
[/B]
i tried finding the current of the 6+10 ohm series resistor that is parallel to R5...
hi everyone,
i need some help with my project that is DC rice cooker. i have the same problem for my calculation and logic cause my rice cooker use 12V and 100Watt. is that mean i need to use 8.3333Amp for the current? or i need to design a circuit that can reduce the amount of current needed...
Hi everyone, so I'm trying to achieve IV curves based on how this website had done below:
http://www.voltaicsystems.com/blog/solar-charger-tutorial-part-2/
But whenever I increase the resistance, the amperage increases rather than decreases! For example, when I use a 500 ohm resistor the...
Hallo,
I have a question which elements are responsible for the increase of tangent delta in a X Capacitor and the reduction of its insulation resistance?
graphite has high conductivity , so i though of making a touch button out of a pencil drawn pattern on the wall.the pattern is shown below.
when not touched -resistance between ends of the pattern >200Mohm (exceeds dmm limit)
when fully pressed - resistance between ends of the pattern = 1.3...
If this is not ok to post then let me know, but I have a question that I feel can only be answered here.
Question: Would it be possible to heat a 50' semi trailer frame to roughly 400F through electrical resistance, I know it would require a lot of power but the reason I ask is because I am...
If an object is heavier.. it has more resistance to inertia..
during seismic movement.. when the ground shakes or accelerates.. does it mean bigger foundation would be more resistant and move less.. and smaller foundation can move more?
Hi.
A simple model explains resistance in metals with collisions of the electrons with the stationary atomic cores. So I assume more collisions result in a higher resistance?
But for the dissipated power we have ##P=U^2/R## , which is large for small resistance. I have difficulties combining...
Homework Statement
Homework EquationsThe Attempt at a Solution
(a) [/B]We can assume for ideal op-amps that there is:
infinite input impedance
low output impedance
the potential for infinite amplification
(b) Non-inverting op amp
(c) This is the part I have trouble with.
There is three...
Homework Statement
We have 1Ω, 2Ω, 2Ω, 4Ω, 5Ω and 6Ω resistors. We have to make a circuit with all of them and total resistance must be 1 ohm.
Homework Equations
Parallel: 1/R1+1/R2=1/R
In series: R1+R2=R
The Attempt at a Solution
I have only made a circuit from 4 resistors:
1 ohm and 2 ohms...
Hello,
Circuit:
1. Homework Statement
Determine the net resistance between points a and c and a and b. Assume R' ≠ R.
Homework Equations
ε - IR = 0
V = IR
The Attempt at a Solution
http://i.imgur.com/Y2KPI20.jpg
I applied an emf between the points a and c, and tried to solve using...
Hi.
Is the resistance of a charged cable different compared to a cable with zero net charge? If it is charged negatively, one could argue that now there are more carriers for the current, so the resistance should be smaller (similarly to water that becomes more conductive if ions are added). On...
I'm not entirely clear what shunt resistance is, it's fairly hard to find things on google which refer to it in the context of LEDs. So we did an experiment in which we measured the IV characteristics of InAs at different temperatures, and observed the gradients of these graphs (apparently those...
According to relativity gravity is just an illusion caused by wrapping of space-time fabric by mass, right? So, what is the elasticity of of space-time? There must be some king of resistance for the wrapping, otherwise even a tiny mass would plunge in the space time for eternity.
Homework Statement
We were given five samples of nichrome wire, each with a different diameter but the same length. A micrometer was used to measure the diameters. We then measured and recorded the electrical resistance, R in Ohms of each nichrome sample with a DMM. I will try to summarize all...
Homework Statement
Assuming the wires have negligible resistance, find the equivalent resistance between the terminals A and B. Answer to 2 significant figures.
Homework Equations
[/B]
1/R = 1/R1 + 1/R2 ... + 1/Rn
R = R1 + R2 + RnThe Attempt at a Solution
[/B]
I have drawn a more...
Using the regression eqn. Find the base resistance of the thermistor.
Find the temp. Of the boiling water using this eqn.
Y=1.54e^-0.059x
How do I go about solving this problem
How exactly do you tell if two elements are in series or parallel? I know that if two elements share two of the same extraordinary nodes then they are in parallel:
But in this example I do not see that. I know for certain that the answer for Rt is:
[ ( (R1 || R2) + R3) || R4 ] + R5
Hi.
Consider a simple circuit consisting of a voltage source ##U## and a load with resistance ##R##, e.g. a lamp or a motor. The current is given by ##I=U/R##. The number of electrons passing the circuit per second is ##n=I/e##. The power consumed by the load is calculated by
$$P=U\cdot...
Homework Statement
Suppose you want to run some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120 V source has a resistance per unit length of 0.0065 Ω/m. If your apparatus draws 2.9 A, what will be the voltage drop across the connecting...
As you know, resistance of a rectangular shape is given by R=ρ A/L
But how do we theoretically calculate the resistance of the bottom case? ( now, the current flow is not parrallel, current flows from bottom through the right side)
I would like to know if there is any references for this...
Homework Statement
Twelve identical wires, each with resistance R = 1.0 ohms, are linked together to form a
octahedron. Find the resistance in an octahedron between opposite vertices and adjacent vertices( A,B for example)
picture
2. The attempt at a solution
I already found the resistance...
Hello everyone,
From what i know electrical resistance for metals is a constant, but in fact it varies with temperature but not voltage. Explanation for metals and temperature is something like "heat, which is in fact average speed of electrons, does obstruct tranmission of other electrons...
In an open circuit, a voltmeter in parallel to a battery measures the EMF. Once the circuit is closed, the measured voltage drops due to both the internal and the external resistance. My question is how can the initial resistor not affect the voltage the voltmeter measures?
Additionally...
Homework Statement
So we are doing an experiment where we are trying to place a 60W light bulb in a room. It is connected to the mains power supply, but we are imagining that it is DC instead of AC. Now we have to make sure that we only loose 0.1% of power in the wires.
Homework Equations
P=VI...
Homework Statement
Find total Resistance
Homework Equations
1/Req= (1/R1)+(1/R2)...
The Attempt at a Solution
Can someone please explain me how 5 ohm R and 3ohm R are in series and then in parallel with the 2ohm R? Thanks
Homework Statement
Determine the resistance of wire at room temperature and at the melting point of the given material.
GIVEN:
Material = Aluminum
Diameter of wire ##= 0.5 mm = 5.0 * 10^{-4} m##
Length of wire ## = 0.5 m = 5.0 * 10^{-1} m##
Temperature Coefficient: ##\alpha = 3.9 *...
Hey, I am having problems with this. I need help with these 2 circuits I am basically lost and not sure how to start. I need to find voltage, current and potency on each resistance
help would be much appreciated, thank you
http://imgur.com/trm1On0
http://imgur.com/a/KD3zr
Homework Statement
A 12 V, 24 W lamp and a resistor of fixed value are connected in some way inside a box with two external terminals. In order to discover the circuit arrangement inside the box a student connects a variable DC power source and an ammeter in series with the box and obtains the...
Homework Statement
You have a 9V battery with an internal resistance of 1.5 ohms. If a 3 ohms load is connected to the battery, how much current will flow through it? When the 3 ohms load is connected, what potential difference will an ideal voltmeter read across the battery's terminals...
Hi,
I am trying to find out series and shunt resistance of solar cell from I-V curve which starts from Isc and going to Voc.
I read some papers and for single illumination mostly said Rs= -(dv/dI)V=Voc
and Rsh= -(dv/dI)I=Isc.
so I am finidng Rs from slope between points from Vmax to Voc, and...