Quick Year 11 Physics Q (1 Viewer)

[Axio]

Hey guys,

So I just want to know why the voltage drop across a resistor is equal to the voltage supply itself (or why is the sum of the voltage drops of the resistors equal to the voltage supply itself)? I understand what it means, I just don't understand why. (And please don't use some analogy about river streams, I actually want to know the physics behind it) Thanks.

 

[xGhanem]

I'm guessing it's due to the law of conservation of energy.
The same amount of energy that was given to the charge has to be lost or transformed in the resistor. aka potential difference.

 

[Axio]

That does make sense.

 

[QZP]

I think you misunderstand the definition of voltage. Voltage is the electrical potential difference between two points. If a power supply supplies 10V, then that means across the entire circuit (from one terminal of the power supply to the other), there is 10 volts of difference. It must then follow that the resistor/loads across the circuit must add up to 10V (a logical argument here) otherwise how can you say the power supply is 10V?

And yes, it is essentially the law of conservation of energy.

 

[Axio]

Ok thanks xGhanem and QZP I think I understand now.

 

[anomalousdecay]

This is why we should have been introduced to Kirchoff's voltage/current laws in year 11.

If you feel at all confused about it, then I suggest you look up KVL or KCL. You can ask me if necessary too.

However, be aware that although KVL and KCL make up the basics and are easy to understand, its uni level stuff.

 

[anomalousdecay]

In response to the message.

It should be covered in year 11, but unfortunately school physics tends to disregard the fundamentals of circuits.

Honestly all you are doing is learning how KVL and KCL work, but they never formally introduce you to it, even though it should be introduced.