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.
In a filter where 1/4 watt resistors is enough would the filter be less noisy if I use 1/2 watt or more or should I use the least wattage resistors needed?
Homework Statement
How much power is dissipated by R1 resistor? (R1=15 W, R2=25 W, V=9 V.)
Homework Equations
I=V/R
P=I^2R
The Attempt at a Solution
Since it is a series 1/Req=(1/R1)+(1/R2)
Then I=V/R= .96 A
so Then i just simply plugged in I in P=I^2R which is...
Homework Statement
Basically, this "battery" is actually a variable voltage source. The current is raised and the voltmeter measures the voltage in the resistor. What is the resistance in the region that the current goes from 1-4 Amps? (BTW, the red line is a best fit line.)
Homework...
ok so if we have an amplifier with direct negative feedback we have a voltage follower
if we put a resistor between that inverting input pin and ground, we can do these things:
if we put another resistor between the output and the inverting input we can adjust the gain
if, instead, we...
Dumb question.
Can't seem to understand how pull up resistor works when interfacing TTL to CMOS.
A TTL output connected to a CMOS input.
TTL output is 3.3V, but CMOS requires 5V.
When TTL output is high, one end of resistor is 3.3V and the other end is 5V.
The 3.3V end is connected to...
How do you find the current through a resistor that is in parallel with 2 other nonequal resistors? I totally forgot how to do this.
as an example, if
E = 10V
R1= 5ohm
R2 = 10ohm
R3 = 15ohm
So, I know that 1/Req = 1/R1 + 1/R2 + 1/R3 = .533ohm
and also know Inet = 10V/.533ohm =...
I'm trying to use a MOSFET as a voltage controlled resistor, and am under the impression that it acts this way when it is in the linear region. However, our VDS will be 2.5V-20V, and our VGS will be 3.6V-5V.
That means our VDS will most likely be greater than our VGS - VT, which means it will...
Homework Statement
What current flows through resistor R1 (350 Ohms) in the figure when the applied voltage is 50 V?
Homework Equations
V = IR ?
The Attempt at a Solution
I would have thought the answer would be zero because I thought the potential at R1 is equal (but this was incorrect)...
Homework Statement
Given a series circuit with a capacitor of capacitance C, a resistor of resistance R, a DC voltage source with a voltage V, and an open switch (by open I mean not connected so no current flows through). At t=0 the switch is closed. How much energy is dissapated by the...
In my lab we're doing some stuff with logic chips and d-flip-flops and in our kit of circuit components are a couple of these red plastic covered strips that have about 12 pins coming out.
Their some kind of resistor strip but question is how do you use them? do you just consider each 2 pins...
Hi,
I need to simplify this circuit of resistors.
Homework Statement
Image of problem:
http://img24.imageshack.us/img24/9206/resistor1.jpg
The Resistor equivalent is 9 ohms, and the solution for R is actually 15 ohms. However, I'm not sure how to get this answer. I think I am...
Hi,
I need help simplifying this circuit with parallel and series resistors. I am mainly confused, because there seems to be a point in my simplification where in picture 4 and 5 of my second image where the remaining 3 resistors are connected by 1 node.
I tried to simplify them as...
Homework Statement
For the circuit shown in the figure, find the current through and the potential difference across each resistor. (Figure attached)
a) Find the current through 4.0 ohm resistor.
b) Find the potential difference across 4.0 Ohm resistor.
Homework Equations
V = IR...
Homework Statement
A flashlight bulb rated at 1.4W and 4.0V is operated by a 9.0V battery. To light the bulb at its rated voltage and power, a resistor is connected in series as shown in the figure. ( i don't know how to paste the picture but its only a resistor and then light bulb in...
A voltmeter with internal resistance of 100k ohm reads 40V across the 200k ohm resistor of the circuit. Determine the actual voltage across the resistor( without the voltmeter)
my anawer:
across 100k ohm = 13V
across 200k ohm = 26.7 V
is it correct ?
but it seems to be wrong..
so...
Hello, I came across a type question and my prof never went through it in the class and unfortunately I couldn't find it in the textbook nor on the internet.
I can find the equivalent capicitance of capacitors in a combination of series/parallel no problem, however when a resistor is thrown in...
Need help finding unique resistor combinations!
Homework Statement
Amps = 30, 45, 60, 70
Voltage = 600 to 700, 600 to 800, 400 to 600
I have three typres of resistors 3 ohm, 5 ohm, 10 ohm
I have to find 17 combinations of resistors to work with the given amps and volts. The resistors...
I'm trying to find the equivalent resistance for this circuit
IIRC, it's a resistor ladder.
I think I've seen this solved by working backwards, but I can't for the life of me remember how to do it now. I've tried rewriting the network in other ways to expose any series/parallel/voltage...
Homework Statement
Hi there I never managed to get a decent set of results in my physics coursework as I was unfortunately ill for the last few lessons of experiment time! My teacher won't let have an extension and won't let me do any more experimenting during lunch hours!
Basically by...
Homework Statement
Consider the circuit in Figure P31.52, in which R = 10 . The 10 resistor is dissipating 48 W of power. How much power are the other two resistors dissipating?
(Image Attached)
5 resistor ________
20 resistor ___24___
Homework Equations
VI=RP
The...
Homework Statement
This is not an actual homework problem but this appears in a couple of more complicated problems that deal with RC circuits and Kirchhoff's laws.The connection consists of a capacitor in series with a resistor. My question is: will the capacitor be instantly charged when...
SOLVED
Homework Statement
What is the value of resistor R in Figure Ex31.21, in which ΔV = 5.0 V and I = 62 mA?
(Image Attached)
Homework Equations
RI=V
The Attempt at a Solution
My attempt at the solution is literally solely the equation above. I can't see any other way to...
Okay, I've been trying to study for my physics final and I've been stuck on this one for a few hours now...it's driving me crazy. There must be a flaw in my understanding of Kirchhoff's Laws.
A link to the circuit can be found here -> http://img410.imageshack.us/img410/7798/resist.jpg...
Hello All,
I'm trying to determine if there is a way to make a voltage controlled resistor using an Op-Amp (or multiple op-amps). I want to use this VCR to control the gain of another op-amp but wanted to see if there was an altenative approach to using a JFETs or an LED/CDS photocell...
Homework Statement
How much power is dissipated by the 12\Omega resistor in the figure?
PR1=______W
How much power is dissipated by the 18 resistor in the figure?
PR2=______W
Homework Equations
P=IV
I=\frac{V}{R}
The Attempt at a Solution
P=\frac{V}{R}*V
P=V2/R...
In the circuit below, the time required (s) for the charge on the capacitor to drop to 47% of its value after the switch is closed is 2.83 s. If R = 1340 ohms, what is C in μF (microfarad)?
(dq/dt) + q/(RC) = 0
(.47q)/(t) = q/(RC)
t/(.47R)= C
Convert C from F to uF by multiplying by...
~~Resistor Concept~~
Hi. I am having trouble with understanding the resistor. What does a resistor do in SERIES or in PARALLEL circuit?
My understanding: ( please correct me if i am wrong!)
In series circuit, Resistor is a device that reduce the current in the circuit. And according to...
Homework Statement
A 10 ohms Nichrome resistor is wired into an electronic circuit using copper leads (wires) of diameter 0.6 mm with a total length of 50 cm. The additional resistance is due to the copper leads is 0.03 ohms.
What change in temperature would produce a change in resistance...
I'm having trouble with Thevenin models, specifically this question where the V_oc is not given.
The problem:
Assume an unknown circuit provides the specified current through the load resistors as given below:
100k - 2.3mA
1.2M - 510uA
Find a Thevenin model for the unknown circuit.
All...
Homework Statement
Two batteries that have emfs E1 and E2 and internal resistances r1 and r2 are connected in parallel. Prove that if a resistor of resistance R is connected in parallel with combination, the optimal load resistance (the value of R at which maximum power is delivered) is given...
Homework Statement
What is the value of the unknown resistor in the circuit shown if the equivalent resistance for the circuit is 21.50 ohms.
Homework Equations
Series= R1+R2+R3...
Parllel= (1/R1)+(1/R2)+(1/R3)...
The Attempt at a Solution
First off, I'm sorry for the horrendous...
I was trying to work out a way to calculate the combined resistance of more than 2 resistors in parallel. We all know the MAD rule for 2 resistors but does this equation work:
combined resistance = sum of resistance * # of resistors-2
I checked wikipedia and there was nothing there above 2...
i have 20 ultrabright white LED's and i want to get a good brightness out of them. they will be in 2 circuits of 10 leds each. i think i need 1 resistor per led but I am not sure which resistors to use. The LED's are 3.2 - 3.8V and 30mA. i plan to use 9v batteries in whatever combination is best...
OK so I am new to these forums so please forgive me for any mistakes. I have a prelab for my electromagnetism class. We just began this chapter in class and the book is harder to understand than the problems! Here's the problems and my shot at them:
1. Homework Statement
1. This...
Homework Statement
(a) Find the equivalent resistance between points a and b in Figure P18.5 (R = 15.0 ).
(refer to physics.gif for parts a. and b.)
(b)Calculate the current in each resistor if a potential difference of 34.0 V is applied between points a and b.
A (4.00 resistor)
A...
I need to find a shunt resistor (basically a low resistance resistor), that can handle 20-25 W, and is less than 1ohm resistance. Not really sure how to find some.. can anyone give suggestions?
I'm trying to work out the correct algorithm for using Kirchoff's rules when using a non-ohmic resistor like a light bulb. The problem is that the resistance depends on the voltage, but the voltage may depend on the resistance (a simple example: a bulb and a resistor in series: how should the...
We need to have a load resistance to match an internal resistance for peak power.. so we've decided to use a Power MOSFET as the varying load resistance, but my question is.. when I'm looking for which power MOSFET to buy, to use, what should I be looking for in terms of properties?
This is...
A blow-dryer and a vacuum cleaner each operate with a voltage of 120 V. The current rating of the blow-dryer is 13 A, and that of the vacuum cleaner is 3.0 A.
(a) Determine the power consumed by the blow-dryer.
1 W
(b) Determine the power consumed by the vacuum cleaner.
2 W
(c)...
resistor value ...
Homework Statement
see the attached diagram
Homework Equations
What value of resistor in the place of the 33 ohm resistor would draw maximum power from the rest of the circuit and what power would it draw?
The Attempt at a Solution
I can figure out the currents flowing...
N resistors (N>2) are connected in parallel with a battery of voltage V0. If one of the resistors is removed from the circuit, which of the following quanities will decrease?
1. the voltage across any of the remaining resistors,
2. the current output by the battery,
3. the total power...
Hello all.
I'm trying to calculate the resistance of a circular resistor with the following specifications:
Doped Silicon with a carrier concentration of 1.6x1025 m-3 (sheet resistance ~ 0.5 ohms/square)
Radius = 200 microns
thickness = 5 microns.
I know the general formula for...
Homework Statement
what is the total impedance and voltage across the resistor at this frequency?
The type of circuit is a simple circuit with a high pass filter connected. The filter is rated at 10nF, the resistor is 1Kohm and the power source is 10v AC
Homework Equations
the...
Is there a device or method for automatically (non manually) varying a resistor?
Basically we have A thermoelectric with an internal resistance, hooked up to a load resistor, and we want peak power (which is when the load resistance matches the internal resistance). Right now we are manually...
Hi all, I want to use a 0 ohm resistor for single-point grounding to connect analog/digital ground together. Since the current could be pretty large (several hundred mAs), I'm considering how to choose the resistor for its power consumption. Yes it's "0 ohm", which makes it seem that any size...
There is an example in the textbook to show the change of entropy. A resistor being held at fixed temperature of 300K. 10 amp current passes through the resistor for 300 seconds. The change in entropy of the resistor is ZERO. The reason written in the book reads since the temperature doesn't...
Homework Statement
For the RC Circuit (R = 1M Ohm, C = 1 Micro Farad and E = 30 V) find the potential difference across the resistor 10 sec after the switch is closed.
Homework Equations
V = E (1 - e^ -t/RC)
The Attempt at a Solution
I use the above equation but I get it wrong...
Homework Statement
the title says everything, any formula that to find resistance in a DC circuit of one resistor and one capacitor connect parallel, as well as the current through each of R and C (the known values are R C and V)
Homework Equations
seem to me i = (V/R)e^ (-e/RC), but...
Resistor & power dissipated question--please help
Homework Statement
Load resistor R is attached to a battery with EMF E and internal resistance r. For what value of the resistance R in terms of E and r will the power dissipated by the load resistor be a maximum?
Homework Equations...