Resistor Definition and 894 Threads

  1. Y

    Engineering Solving Diode Resistor Circuit Homework

    Homework Statement Find Voltage/Current across each diode: ----R--- |...| V...D |... | ----R--- Repeat 50x until...
  2. B

    Solving Circuit with Large Resistor and Inductor: Q = CV?

    Homework Statement Hello: I've this circuit: -----Resistor (100000 ohms)---/ (switch) ------- | | |A Battery Capacitor Inductor | |...
  3. D

    Finding Resistance of Ohmic Resistor with Voltmeter and Household Items

    Can someone explain how I can find the resistance of an ohmic resistor of unknown resistance by setting up a simple circuit using a voltmeter and household appliances? Thanks
  4. M

    Which Wattage Resistor is Best for a Noiseless Filter Design?

    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?
  5. T

    Power dissapatied by a resistor

    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...
  6. N

    Finding resistance in a resistor?

    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...
  7. C

    Amplifier negitive feedback capacitor and resistor in paralell

    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...
  8. L

    How do you decide the value of the resistor?

    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...
  9. J

    Calculating Current Through a Parallel Resistor Circuit: Help Needed

    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 =...
  10. A

    In what region (linear,saturation) does a MOSFET act as a variable resistor

    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...
  11. X

    R1 350 Ohms: What Current Flows at 50V?

    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)...
  12. E

    Energy dissipated by a resistor in an RC circuit

    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...
  13. F

    What is this weird protoboard resistor strip thing? dumb question yep

    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...
  14. N

    Parallel and Series Resistor Simplification HELP

    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...
  15. N

    Parallel and Series Resistor Simplification

    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...
  16. R

    Find the current through and the potential difference of resistor

    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...
  17. A

    What Resistor Value Is Needed to Power a 1.4W, 4.0V Bulb with a 9.0V Battery?

    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...
  18. K

    Calculate Voltage Across Resistor Without Voltmeter

    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...
  19. F

    Equivalent Capicitance (with a resistor)

    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...
  20. T

    Need help finding unique resistor combinations

    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...
  21. S

    Tips on solving resistor ladders

    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...
  22. E

    Light dependent resistor experiment

    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...
  23. P

    Power Dissipation in Resistors: P31.52

    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...
  24. B

    Capacitor and resistor in parallel

    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...
  25. P

    Calculate Value of Resistor R in Ex31.21 | ΔV = 5.0V, I = 62mA

    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...
  26. U

    Why Is My Calculated Current Through R1 Incorrect According to Kirchhoff's Laws?

    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...
  27. J

    Can Op-Amps Create Effective Voltage-Controlled Resistors?

    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...
  28. C

    How Much Power Does Each Resistor Dissipate?

    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...
  29. C

    Discharging a capacitor through a resistor

    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...
  30. I

    Resistor Concept: Series & Parallel Circuits

    ~~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...
  31. H

    Nichrome Resistor and Copper wire

    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...
  32. B

    Thevenin without removing load resistor

    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...
  33. W

    How Is Optimal Load Resistance Calculated in Parallel Battery Circuits?

    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...
  34. S

    Finding unknown resistance of a resistor using a schematic drawing

    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...
  35. H

    Calculating Combined Resistance in Parallel Circuits

    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...
  36. L

    LED and Resistor Circuit WiringWhich resistors should i use?

    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...
  37. G

    Several basic resistor prelab questions

    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...
  38. S

    Calculate the current in each resistor

    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...
  39. A

    Need help locating high power shunt resistor

    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?
  40. H

    Apply Kirchoff's rules with a non-ohmic resistor?

    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...
  41. A

    Power MOSFET as a voltage controlled resistor

    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...
  42. J

    How to Calculate Power and Energy Usage in Electrical Devices

    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)...
  43. M

    Find Max Power From Circuit: 33 Ohm Resistor

    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...
  44. J

    Resistor removed from circuit, which of the following will decrease?

    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...
  45. J

    Resistance of a Circular resistor

    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...
  46. W

    Calulating voltage across a resistor

    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...
  47. A

    A way to automatically adjust a variable resistor?

    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...
  48. R

    0 ohm resistor selection for single-point grounding

    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...
  49. K

    Change of entropy in a resistor

    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...
  50. L

    Finding expresion for current through resistor

    I want to find an expression for I_5. I see that I_{S1} = I_4 - I_5, but how can I proceed from here?
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