Resistor Definition and 879 Threads

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...

How can i determine resistors are connected in parallel or in series? By current or potential.difference? The following are some complicated example..

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

What is the purpose of placing a limiting resistor infront of an LED?

[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...

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...

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...

Q:can anyone explain heating effect E=I2Rt? and heating effect in a resistor?

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

Homework Statement Show that the equivalent resistance is Req = 1/2 [(4RtRl + Rt^2)^(.5) + Rt] http://img74.imageshack.us/img74/5905/pingib2.png Homework Equations The Attempt at a Solution So far all I can get is Req = Rt + Rl Rt/(Rt+Rl) from the first three resistors starting from the...

Hi. I've no idea how to answer the following questions. Could someone please help? I'd really appreciate it. 15.15 A capacitor is joined in series with a resistor, a low resistance microammeter, a switch and a 12 V battery. (a) When the switch is first closed, what is (i) the p.d...

I am working on getting an MSHA approval for a device and I would like to estimate what the surface temperature of a resistor will be over time. Is there a way to calculate the surface temperature (temp change per unit time perhaps) of a known resistor if a simple DC voltage is applied...

I am having a great deal of trouble solving the following problem. Can anyone help? A straight wire of mass 10.2 g and length 5.0 cm is suspended from two identical springs that, in turn, form a closed circuit (Fig. P19.66). The springs stretch a distance of 0.51 cm under the weight of the...

I'm hoping this is the right forum for this question, I've never been to this part of PF before. I've taken up some interest in working with LED lights but I'm slightly confused with how to build the circuits for them. I'm told you need to put in a resistor to keep the LED safe from high...

I've read of resistors being referred to as four terminal devices, and capacitors being referred to as 3 terminal devices, can anyone explain this? or point me to a source that explains it, I can't find anything about it online.

hi, can anyone help me with this problem? i need to try find the current in the 50ohm resistor marked with an 'x'. any help would be greatly appreciated!

In a circuit where there is one resistor in one path and a separate path with no resistance, will all of the current go through the second path?

find resistance between A & B :bugeye: I'm sure it's not 1 ohm but i don't know how to solve http://www.pantip.com/cafe/wahkor/topic/X5389102/X5389102-1.jpg

What do I have to do to calculate the value of the unknown resistor? The galvonometer reads 0 AMPS. I don't understand how the galvonometer changes according to where it's connected to the resistance wire. I thought amp meters read the same no matter where they're connected in the circuit. Just...

Homework Statement I have a resistor and an inductor in series. The current across each is the same, correct? I want to know if I can use Ohm's Law to solve for current across the inductor if I know the Voltage and inductive reactance. Basically, does I = V/X_{L} ? Homework Equations V...