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.
Homework Statement
A capacitor with initial charge q0 is discharged through a resistor.
(a) In terms of the time constant τ, how long is required for the capacitor to lose the first one-third of its charge? answer x tau
(b) How long is required for the capacitor to lose the first two-thirds...
Homework Statement
A resistor, capacitor, and inductor are connected in series across an AC generator. Which of the following statements is true?
The power delivered by the generator does not depend on the phase difference between the generator voltage and current.
All the power is lost...
when i connect a sinusoidal voltage source to resistors all voltages and currents become zeros.
another problem is how to plot the voltages and currents for any component.
if anybody has a book or link it would help please reply. thank you
check the attached picture
Homework Statement
So I got this homework to do, and I've pretty much figured it all out using a bus diagram, except for one part. I don't know how to approach Resistors 7 through 9 and 10 through 12. The only idea that I have is that they equalize between 7 and 8, and 10 and 11.
This...
Homework Statement
A 0.25 UF capacitor is charged to 50 V. It is then connected in series with a 25 ohm resistor and a 100 ohm resistor and allowed to discharge completely.
Homework Equations
P=I V=I^2R=(V^2)/R
The Attempt at a Solution
i'm not sure how to approach this problem. it...
Homework Statement
The two solenoids in the figure are coaxial and fairly close to each other.
While the resistance of the variable resistor in the left-hand solenoid is increased at a constant rate, the induced current through the resistor R will
A - flow from a to b.
B - flow from...
Homework Statement
A battery has an EMF of 12.0 volts and internal resistance of 3 ohms
A 21.0 ohm resistance is connected to the battery.
0.5 Amps flow through the battery, hence 0.5 Amps flows through the 21.0 ohm resistor
The potential difference across the 21 ohm resistor is 10.5...
v1 of battery1 is higher than v2 of battery2
The circuit is arranged in a parallel way with 3 layers where the only
Resistor is in the middle layer.
battery1 is on the top layer and the only resistor is on middle layer
Battery2 is on bottom layer.
The terminals of the battery is not facing...
A 10 ohm resistor in a series with a bulb and a 12v source.
a) If the 8.0V is across the bulb, what is the voltage across the resistor?
I wrote 4v, is this correct?
b) What is the current in the circuit? I wrote 1.5A, is this correct?
c) What is the resistence of the bulb? Could...
Hi all,
I'm doing a lab now to determine the relationship between the resistance of a resistor (colour-coded ones) and the energy and power dissipated. What kind of relationship is expected between the variables R and P, or R and E?
The way I carried out the lab was to use different...
I am building a 2 to 4 decoder with 7408 And gates and need to put LED's on the output as indicators, active high. 2 questions
1. Would I put a current limiting resistor in series with the LED to ground or put the resistor and LED from the gate output to Vcc?
2. The LED draws 30mA at 2V...
Hi this is my first post so please be nice :)
1. Homework Statement
The problem has been set up that a circuit containing a resistor and switch is being driven by a power source of unkown potential. The switch is flick to short the power source leaving only the resistor in a closed loop...
http://img366.imageshack.us/img366/4260/note0002ku2.th.jpg
I don't understand how can I draw a new network finding the equivalent network.
Are there any techniques that I have to know?
Also, can the technique also applied to capacitor network finding equivalent capacitor network~...
This is definition of resistor from Wikipedia.
1. " A resistor is a two-terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in proportion to the current"
And this is another mention about Ohm's Law from a diagram of Wikipedia...
Homework Statement
A 2.80-k W resistor and a 4.60-mF capacitor are connected in series across a 46.0-Hz AC generator. What is the impedance of the circuit?
Homework Equations
Z = sqrt ( R^2 + (XL -XC)^2)
Xc = 1/wC = 1/ 2*pi*46.0 Hz* 4.60uF
XL = wL
The Attempt at a Solution...
Homework Statement
a 200 volts battery is connected to three resistors as shown, see attachment.
a) what is the potential drop across the 32 ohm resistor?
b) the 10 ohm resistor is immersed in 60 grams of water at 20 deg celsius. how long much current flow for the water to reach 40deg...
Homework Statement
a current of 5 ampere exists in a 10 ohm resistor for 4 minutes
a) how many coulombs pass through the resistor in this time? should be 1200 coulombs
b) how many electrons pass through the resistor in this time? should be 7.5*10^21
c) what potential drop exists across...
I understand that a resistor can lower current flow at the expense of heat.
So essentially a resistor eats up/throws away energy?
Isn't there a better way to change current flow without throwing away energy?
Thanks!
...Vern
Homework Statement
Consider a circuit consisting of a voltage source with V = V_0 \sin{\omega t}, a resistor, a capacitor, and an inductor, all connected in series. The problem is to find the steady state current as a function of omega.
Homework Equations
V = IZ
Z = Z_R + Z_C + Z_L...
I have an oven and the heater element is ran by a watlow controller. It is going out evey two or three years. The watlow controller runs a relay to turn element on and off. The relay on the watlow needs a load of 100ma min. to keep contacts clean. I have the resistance of the coil for the on off...
Homework Statement
2ohms 4ohms 3ohms and 9ohms are connected across an 8-V DC source. what is the current through the 9ohm resistor
Another problem is
A 100 V DC signal is applied to four resistors. the values of the resistors are 20ohm 40ohm 60ohm and 80ohm. what is the voltage across...
Homework Statement
http://img126.imageshack.us/img126/6400/picex8.jpg"
Determine the maximum power that can be delievered to the varaible resistor R in the circuit of Fig 4.139.
Homework Equations
The Attempt at a Solution
I am not sure how to handle this because the...
So, if Jimmy adds a resistor in parallel to a circuit with two other resistors...
Homework Statement
wouldn't the resistance decrease?
Homework Equations
The Attempt at a Solution
[SOLVED] Battery with internal resistor
Homework Statement
What is the current in a 8.25 ohm resistor connected to a battery that has a .21 ohm internal resistance when the potential drop across the terminals of the battery is 6V?Homework Equations
R_{s}=R_{1}+R_{2}...
V=IR
The Attempt at a...
Ok, I'm doing an electronics assignment at the moment and we'e just been getting into first order filters and the like. As a little demo/experiment thing, we were asked to measure the voltage drop across a single variable resistor being powered by a 9V DC supply. We were then told to twist it...
Homework Statement
A 2.8k-ohm and a 2.1k-ohm ersistor are connected in parallel; this combination is connected in series with a 1.8k-ohm resistor. If each resistor is rated at .5W, what is the maximum voltage that can be applied across the whole network?
Homework Equations
Ohm's Law...
Homework Statement
Three 100 resistors are connected as shown in the figure. The maximum power that can safely be delivered to anyone resistor is 28.0 W.
"http://imageshack.us
Homework Equations
P = VI
The Attempt at a Solution
I found the total resistance of the circuit, but i don't...
There is a diagram for this question, but I can't post it, so I just describe it. There are four resistors R1,R2,R3,R4. When the switch S is opened, current only flows through R1,R3 and R4. R3 and R4 are parallel to each other, but in series with R1. Now the switch is closed, what happens to the...
Homework Statement
This is an experiment Ill have to write up later, unfortunately I was out for 2 weeks of lectures due to illness. This is the experiment;
Find the values of capacitance C and resistance R in a series combination, given he following apparatus;
1. the unknown RC...
[SOLVED] Finding the unknown resistor using only an ohmmeter
In a box there are 12 resistors, 11 of them have a resistance of exactly 1 ohm, and 1 of them doesn't. Using only an ohmmeter, what's the least measurements you can make to find out which one is the odd resistor and what's its value...
A carbon resistor is to be used as a thermometer. On a winter day when the temperature is 4.00(Degree C.), the resistance of the carbon resistor is 218.0(Greek "w') . What is the temperature on a spring day when the resistance is 215.8(Greek "W")?
Take the temperature coefficient of resistivity...
Homework Statement
an npn transistor is used to drive a constant current I through three ‘white’ LEDs, connected in series. If the required current value is I = 25 mA, and the current-gain of the transistor is β = 300, find the value of the resistor R, giving your answer to 3 significant...
Can someone give me a reply Intro Physics style? :D
P = IV is known as the "power of the circuit" right?
But then, we have questions asking about the heat dissipated by a resistor. We can use P = IV, P=I^2 R , or P=V^2/R to answer such questions
Since the voltage drops all add up to...
Tolerance rating on a 0 Ohm resistor?
I'm just curious why the zero ohm "jumper" resistors I use have a tolerance rating of 5%. This doesn't really make sense to me because 5% of 0 Ohms is still 0 Ohms. I understand that even a close to ideal conductor is not going to be 0 Ohms, but why do...
hi! I need some assistance regarding my assignment. hope there's anyone who could help me out. the questions are:
1.a. a 12 ohms resistor is connected in parallel with a series combination of resistors of 8 ohms and 16 ohms. if voltage drop across the 8 ohms resistor, is 48 volts. Determine...
i am currently doing my as level coursework and for part of it i need to work out what size resistor to use in a potential divider but i have no idea how anyone that could help i would be really grateful,,
thanx
steph xx
http://xkcd.com/356/
"I first saw this problem on the Google Labs Aptitude Test. A professor and I filled a blackboard without getting anywhere. Have fun."
Discuss.
Homework Statement
A resistor with resistance R and a capacitor with capacitance C are connected in series to an AC voltage source. The time-dependent voltage across the capacitor is given by V_c(t) = V_c_0 sin(wt).
A) What is the amplitude I_0 of the total current I(t) in the circuit?
B...
[SOLVED] Simple resistor problem
Edit: Oh bullocks! Just noticed the thread title is: "simple resistor problem" when it's obviously supposed to be transistor. Can't seem to be able to edit the topic, though.
Homework Statement
The problem statement is as follows:
Find the value of the...
Hi all,
I am meant to find the total impedance across the circuit but am having trouble with one section of the circuit. This section comprises of 2 resistors and 1 capacitor in parallel.
The two resistors are 8 ohms each and the capacitor is 3 ohms. So the process is meant to be:
Z = (...
Hi guys,
I need to build a REALLY simple amp for a friend. I only want to use a resistor and a transistor plus the normal stuff(battery and speaker). Please help.
Thanks in advance,
Circuit Man
The figure shows six identical bulbs connected to an ideal battery. All the bulbs are glowing
Please see attached file.
Rank in order, from brightest to dimmest, the brightness of bulbs A to F.
Thank you
copy from Physics for Scientists and Engineering with Modern Physics by Randall D. Knight.
The figure shows six identical bulbs connected to an ideal battery. All the bulbs are glowing
Please see attached file.
Rank in order, from brightest to dimmest, the brightness of bulbs A to F.
Thank you
copy from Physics for Scientists and Engineering with Modern Physics by Randall D. Knight.
--------------------------------------------------------------------------------
If a charged capacitor c=35 micro farads is connected to a resistor R=120 ohms how much time will elapse until the voltage falls to 10^6/D of its original max value?
Ciruit contains a switch, resistor, emf and...
Homework Statement
A 6V DC voltage source is connected across both a 5kohm resistor and a 10 nF capacitor in series. The voltage drop across the resistor is what?
Reply With Quote
Homework Equations
Q=CV
The Attempt at a Solution
Q= (10*10^-9 F)(5000ohms)
Homework Statement
The circuit in the drawing contains five identical resistors. The V = 50 V battery delivers 46 W of power to the circuit. (Picture should show up somewhere)
Q: what is the resistance in each resistor
Homework Equations
so far the only things i have...
can someone please post an e-link to a site having tough and conceptual resistor and capacitor problems with all the tips and trick(to solve fatsly :rolleyes:).
please