# Questions tagged [ohms-law]

A well known relationship that describes the relationship between Voltage and current through a device's resistance expressed mathematically as V= IR. This formula says that voltage across the device is equal to the current through the device multiplied by the resistance.

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### If adding resistors in parallel decreases total resistance, why doesn't the voltage in the circuit change?

I'm sure I'm missing something basic, but here we go: If adding resistors in parallel decreases total resistance, why doesn't the voltage in the circuit change? Does the current increase to match ...
2answers
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### Double the voltage did not double the amps?

I have two brand new AA batteries. I measured the voltage and current of each battery and they are both 1.5v and 5A respectively. I connected these same batteries in series and I measured the voltage. ...
1answer
77 views

### Fraction resistance and negative resistance

Is it possible that the resistance will be fraction or negative number and what's happened?
2answers
80 views

### Why lights dim when the AC compressor switches on

If two points in circuit are not connected there is supposed to unlimited resistance between them. So when the compressor is added to circuit it is either very high resistance or very low. In either ...
2answers
203 views

### Basic circuit analysis question [duplicate]

Why current is negative in this situation? Because EMF and current directions are the opposites? simulate this circuit – Schematic created using CircuitLab Can someone give me a good ...
2answers
430 views

### How does one determine the voltage of a node?

This sounds like a very straightforward question, and probably has an obvious answer. I've read a section in a physics book on electricity, I've read a textbook on DC and this simple concept seems to ...
1answer
2k views

### Should I use a resistor in this scenario?

I am building a IR pen and wondering if I need a resistor for this. Here is my specifications for my IR LED: Forward Voltage: 1.2 V Forward Current 100 mA So on and so on. I am powering it with a AA ...
1answer
50 views

### Short and Open Circuit Calculation

Suppose there is a ideal voltage source which can provide infinite power if that is needed in an ideal scenario. Now suppose a resister R is connected across it and the e.m.f is E. So by ohm's law the ...
4answers
218 views

### Ohm's Law and Death [duplicate]

So I bought an Arduino today, my high school grades were terrible but I decided to dive into electronic engineering anyway. I am a total noob so please forgive me. So Ohm's law states v = R * I, ...
2answers
60 views

### What damage can 1500V cause to a circuit? [closed]

I'm working on a device that has a supply of 220 V. The output has an LED at the end of a fibre-optic cable coming from the device in question. If, for some reason, a tremendous amount of voltage ...
2answers
18k views

### Voltage drop through a resistor using Ohm's Law?

I'm having a very hard time comprehending basic Ohm's Law. I was recently watching a video on the operation and use of Operational Amplifiers, and was completely lost because I couldn't understand ...
2answers
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1answer
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### Molybdenum Heater Wire

I have a 12 foot length of 14-gauge molybdenum wire that I have measured a resistance of 1.2 ohms. I would like to use it as a small heater coil. How can I calculate the safe number of volts that I ...
1answer
1k views

### Parallel circuit-find value of resistor [closed]

I have a parallel circuit with 7.5 ohms as total resistance,75 volts, with 2 resistors. R1=10ohms,R2 is unknown. How can I find the value of R2?
3answers
205 views

### Is it possible voltage without current and opposite [closed]

I got really surprised by seeing this possibilities from a power, energy calibrator is it really injecting it by violating the laws what we use in practice? See the photos? If anyone knows it please ...
1answer
166 views

### Is Ohm's law required to calculate Watts?

A buddy and I were having a conversation. One of us is convinced that Ohm's Law and Watts are the same thing. After much research I can not find anything directly pointing Ohm's Law to defining Watts, ...
5answers
256 views

### Ohm's law to calculate voltage [closed]

I know this is a bad idea in practice, I'm more concerned with the theory. How would you use ohm's law to solve this problem. Given V = IR I have a 12v 10amp DC power supply. I want the output ...
1answer
724 views

### What can cause a resistor to become non-ohmic?

Can anyone help me find some causes as to why a resistor may become non-ohmic? Thanks in advance.
1answer
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### How would i go about finding Rl when rl is r3

How would i go about finding Rl :/ I'm so lost iv looked for examples and all they have done is confuse me
2answers
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### Volts for power supply, and ohms and watts for the resistor [duplicate]

I'm very new on this for this has never been taught in my school. I have ten 5mm blue LEDs. Each led has 3.4V and 30mA max current. The only thing I know is that I have 34V for my LEDs. The power ...
2answers
86 views

### calculating Power

I wanted to ask, if I have a electrical component with a power rating of let's say 5W does this mean it would dissapate 10W after 2 hours and 15 W after 3 hours?? or is it correct to say it dissapates ...
2answers
925 views

### How does electrolytic capacitors work?

Basically I am interested about the polarity of an electrolytic capacitor.How is the polarity of an electrolytic capacitor is defined and what if I reverse the polarity in a simple circuit containing ...
2answers
119 views

### 9 Volt battery connected with no resistance but current is not 9 A?

As per Ohms law , V = IR OR I = V/ R So if I set R to 0 , then V should be equal to I ? However when I connect 9 Volt battery poles to each other with multimeter in between the reading says 0.2 A.
2answers
399 views

### Ohms to volts i [closed]

Hi I am not sure if I understand this! Ok if I have a power source of 5 volts which then has a resistor of 6ohms and another resistor of 4ohms in parallel with a volt meter would I add the two ...
1answer
52 views

### I dont know how to caculate initial current [duplicate]

simulate this circuit – Schematic created using CircuitLab I have a circuit of just a 240 ohm resistors and a 12 v battery. In the circuit the current after the resistors is 0.05. what is the ...
1answer
142 views

### How to find the current in a complex circuit with nodal voltage sources?

This is circuit. Not sure how to get V, and find current. Any help?