A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate transmission lines, among other uses. High-power resistors that can dissipate many watts of electrical power as heat, may be used as part of motor controls, in power distribution systems, or as test loads for generators.
Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity.
Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds and forms. Resistors are also implemented within integrated circuits.
The electrical function of a resistor is specified by its resistance: common commercial resistors are manufactured over a range of more than nine orders of magnitude. The nominal value of the resistance falls within the manufacturing tolerance, indicated on the component.
I noticed that, for resistors in a parallel circuit, where R1 is < R2, the minimum value is (R1)/2, and the maximum approaches R1.
I was trying to work out why, so for two resistors, the calculation is:
R1.R2/(R1 + R2).
I thought of partial derivatives but not sure where to go after that, and...
Homework Statement
Two resistors when connected in series to a 110 V line use one-fourth the power
that is used when they are connected in parallel. If one resistor is 2.0 kΩ, what is the resistance of the other?
Homework Equations
V=IR
The Attempt at a Solution
v=ir...
Homework Statement
In Figure 27-72, an ideal battery with an emf of = 14.0 V is connected to a network of resistances with R1 = 7.00 , R2 = 12.0 , R3 = 4.00 , R4 = 1.00 and R5 = 6.00 . What is the potential difference across R5?
FIGURE:
|----**R1**---|
|...
Homework Statement
If I have a circuit with some resistors and then the circuit branches out in parallel where one route has a resistor (rA) and the other route does not, would I still incorporate the resistor (rA) in the calculation of the total resistance of the circuit?
Homework...
In a 4-wire (kelvin) measuring system, why are there "sense" resistors? I understand that because there is very little current on the sense line there is no voltage drop. What purpose do they serve?
Homework Statement
I want to know that if there is a voltage drop across a resistor, why is it that voltage increases as resistance increases (Ohm's law)?
Homework Equations
None.
The Attempt at a Solution
N/A
hi guys,
I know this sound strange but it did happen. I was working on a question asking about calculating the resistance of a resistors, using different material one is copper and another is aluminium. I got the right answer, and wrote down the formula and steps that I used. But then I only...
Homework Statement
[PLAIN]http://img534.imageshack.us/img534/228/helps.png
I have trouble completing (b), as I do not know how to solve for the damping factor in this circuit, and hence cannot characterize this system. I have the poles of the system, where s ~= -3048.059 and s~= -8201.941...
Most arrangements I've seen have a power source hooked up to a resistor hooked up to a capacitor. Like this
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capchg.html
Why? I mean, why can't we directly hook the capacitor to the emf?
sounds stupid, I know.
Also, resistors follow...
Homework Statement
a conduction coil with 2 resistors are connected, according to the drawing. write the expression for the potential difference Vac over the coil after t seconds after the switch is closed.
Homework Equations
The current at any time: (a) i=I(1-e-Rt/L)
The electro motive...
I'm having problems with this:
Jed has two resistors, R1 = 120.0 ± 0.30 Ω and R2 = 65.6 ± 0.15 Ω. Give all answers to 2 significant digits.
(a) Calculate the RSS uncertainty for the resistance of these two resistors in series.
(b) Calculate the RSS uncertainty for the resistance of these...
Homework Statement
A 2.7 kOhms and a 3.8 kOhms resistor are connected in parallel; this combination is connected in series with a 1.5 kOhms resistor.
If each resistor is rated at 0.9 W (maximum without overheating), what is the maximum voltage that can be applied across the whole network...
Homework Statement
Provided that the output voltage is 4V, which one or more resistors can be removed to get the same output voltage.
Homework Equations
V=IR
The Attempt at a Solution
Im not sure if any working out is necessary here or not
Homework Statement
I'm confused, like if there's a resistor in a closed circuit with a high resistance, does this mean that there is less current passing through it, and an increase in potential difference across this particular resistor and there is less power delivered?
And for a resistor...
Homework Statement
A battery , ammeter with resistance , 1 ohm and a resistor are connected in series .A voltmeter of 500 ohm is connected parallel to the resistor . The actual resistance of R is 100 ohm , what is the ratio of (the resistance R determined)/(the actual resistance of R) ...
Questions: A certain copper wire has a resistance of 10.0 Ω. At what fraction of the length L must the wire be cut so that the resistance of one piece is 5.0 times the resistance of the other?
What is the resistance of the longer piece? Shorter piece?
I am completely lost on this. i know...
Homework Statement
Two batteries and three resistors are connected as shown in the figure .
http://session.masteringphysics.com/problemAsset/1122583/1/Walker.21.52.jpg
A) How much current flows through 6.0 V battery when the switch is closed?
B) How much current flows through 9.0 V...
Homework Statement
Suppose the three resistors in the circuit have the values R1 = 180, R2 = 220, and R3 = 350, and that the emf of the battery is 18.0 V
http://session.masteringphysics.com/problemAsset/1126258/3/5416321031_128.jpg
Find the potential difference across each resistor...
Homework Statement
The capacitors in the figure are charged and the switch closes at t=0s. At what time has the current in the 8 ohm resistor decayed to half the value it had immediately after the switch was closed?
(The circuit looks something like this; 2 capacitors are in series at...
The effect on current flow and voltages across resistors for
- resistors connected in series
- resistors connected in parallel
can anyone help me and tell me the diffrences?
Homework Statement
R_1 = 70 \Omega, R_2 = 144 \Omega, R_3 = 237 \Omega, R_4 = 117 \Omega, R_5 = 246 \Omega; V_{ab}=43 V
I am looking for the voltage of each resistor as well as the current passing through each one.
Homework Equations
Kirchoff's Voltage/Current Laws: The sum of any...
Homework Statement
http://www.sewanee.edu/physics/PHYSICS102/Ch28.pdf
On this link, can anybody explain to me how to set up problems 1-5?
The answers are on the page, but I have no idea how to group the resistors together to find their equivalent resistance...
Please I've been working on...
Find the effective resistance (resistance between a and b) of an infinitely long ladder of resistors, as shown in the figure, each having resistance R.
http://people.tamu.edu/~malindenmoyer/fig.jpg
The point is that the input resistance which we do not yet know--call it R--will not be changed...
if my 12volt motor running with 12v draws 10amps, am i right in thinking if i put 6 volts on the same motor then it would run at half speed? how would i work out the value of the resistor needed?
i know i need to use ohm's law somehow but it's been a while since I've had anything to do with...
Homework Statement
Consider the group of resistors shown in the figure below, where R1 = 4.4 Ω and E = 8.7 V (that is supposed to be the greek "E" that looks like a backwards "3")
Find the current for each resistor:
Homework Equations
V = IR?
E = I(R1 + R2 +R3...)?
The...
Homework Statement
See attached figure.
All resistors have the same resistance of 2.00kilo-Ohm. Assume V = 12V. Calculate the current through resistor R6 and resistor R5.
Homework Equations
V = IR
I = V/R
R total (series) = R1 + R2...etc
1/R total (parallel) = 1/R1 + 1/R2...etc...
I'm wiring together 25 rgb leds, each take 3V and I was wondering what would be the most efficient way to wire up as many as possible off one power source using resistors. Which resistors should I use? Series or Parallel? 9V or 12V battery?
This is for a small project I'm working on myself...
Homework Statement
http://session.masteringphysics.com/problemAsset/1122583/1/Walker.21.52.jpg
This is the drawing for the problem
The two questions are:
1) How much current flows through 6.0 V battery when the switch is closed?
2)How much current flows through 6.0 V battery when the...
Homework Statement
http://img8.imageshack.us/img8/4413/81107636.jpg
i'm a noob, and i am having trouble adding resistors. this circuit can be reduced to 1 resistor. what is its value?
Homework Equations
parallel: 1/Rtot=1/R1+1/R2+1/R3+1/R4
series: Rtot=R1+R2+R3+R4
The Attempt at...
Homework Statement
We are given currents ia and ib, 4A and 2A respectively. We must find ig and vg (tough). I understand how to do b and d easily once I get the unknowns (ig and vg), that's what I need help with.Picture >
http://img210.imageshack.us/img210/3667/1000943d.jpg
The Attempt at a...
Homework Statement
I have been stuck at the following question for some time now. All help is appreciated.
Homework Equations
P=IV, V=IRThe Attempt at a Solution
I have resolved the right side of the circuit into a 10 ohm resistor. I have also found the current in the 20 ohm resistor (0.4A). I...
Hello, this is my first post here! I am building a bicycle-driven generator using an alternator and battery (12v) pulled from a dead car. I can easily spin it up to the point where the alternator self energizes and produces output, but on a dead or low battery, the load on the alternator is so...
Hello,
I've read that metal film resistors are better than carbon film because they're resistance remains constant even when they heat up from being soldered. And I know they're suppose to be more precise with a 1% variance instead of 5% of the carbon films.
I know capacitors go bad - do...
Homework Statement
Homework Equations
Resistors in Series = R1 + R2 + R3... = Req
Resistors in Parallel = 1/R1 + 1/R2 + 1/R3 ... = 1/Req
The Attempt at a Solution
Studying for a test. This sample exam went pretty well. I am having trouble with 3 out of the 20. I can't figure...
Homework Statement
For the circuit shown in the figure below, C = 7.50 µF, script e = 80 V, and R = 400 Ω. After having been at contact a for a long time, the switch throw is rotated to contact b.
a.)What is the charge on the upper plate of the capacitor just as the switch throw is moved...
Homework Statement
So I have a pentagram of resistors, one in each branch of resistance "r". Each joint is also connected to the two joints across from it but none of the wires inside the pentagram are connected. I need to find the resistance between any two adjacent joints.
Homework...
This is a conceptual problem
Consider a circuit where 2 resistors are connected in parallel, which are in turn connected to another resistor in series. Let the resistance of the two resistors in parallel be R_1 and R_2. The resistance of the resistor in series is R_3
Normally we would add...
At the atomic and molecular level, why exactly does a resistor give off heat?
I'm trying to understand the fundamental science acting behind this device.
I read that when treated like water, forcing water through a bottleneck creates increased pressure on the smaller diameter pipe which...
Does the heat dissipated in a resistor necessarily depend on the direction of current through it? As far as I know the heat dissipated equals square of the magnitude of current thru resistor multiplied the resistance of the resistor. But it seems direction matters.
Homework Statement
In the figure, R1 = 99 . R2 = R3 = 49.5 . R4 = 75.0 , and the ideal battery has emf script e = 6.00 V.
What is i in R1?
Homework Equations
V=IR
Junction Rule
Loop Rule?
i = E / (R+r)
The Attempt at a Solution
The Loop Rule states that for any loop in a...
Three resistors and a capacitor are in a circuit with a battery:
R1 = 23 Ω
R2 = 13 Ω
R3 = 15 Ω
C = 6.2 µF
V = 17 V
The switch has been closed for a long time. What will the charge be on the capacitor 195 μs after the switch is opened?
picture...
Homework Statement
What single, equivalent resistor could replace all of the resistors in this circuit?HELP: If you study the diagram, you will see one pair of resistors which is in parallel. Replace this pair with a single equivalent resistor and re-draw the circuit.
HELP: If you have...
Homework Statement
1.The equivalent resistance of several resistors connected in parallel is always lower than the smallest valued resistor.
A) True
B) False
2. The following two circuits are equivalent at terminals A-B.
http://img6.imageshack.us/img6/1401/circuity.jpg
A)...
http://img42.imageshack.us/img42/1774/67916352.png [/URL]
1/R = 1/R1+ 1/R2 - Parallel Resistors
3. I thought it was 1048 but that was just because I thought 542*2 I really had no idea how to work this
http://picasaweb.google.com/devanlevin/DropBox?authkey=Gv1sRgCL_4l4PpvP_YsQE&pli=1&gsessionid=0QnHbYBvT-aZ60wV9tvsow#5376537235623432578
in the above diagram, how do i add all the resistors( and i know that the dagram has capacitators) in order to find the total reststance,
i know that...
So i decided to get this teach yourself kit on how to use capacitors and resistors and a stamp chip or something like that. Its working great and I'm making LED's flash and stuff...but it uses a serial interface to load the program I make into the stamp.
My question is, if i have a real thing...