will changing the resistance also change the potential difference(voltage)?

Question

also expln ; does the voltage change after passing thru a resistance?

Answer 1

The question itself is a little confusing, but let me tell you how I understand things:

Potential difference is the driving force you apply on the electrons which are trying to pass through a system(circuit) which is resisting the flow of electrons.

The resistance is how much the system is resisting the flow (obviously)

Now, if you have a series circuit with more than one resistor, the driving force (voltage) will be shared among the resistors depending on their resistance values. So, if you apply a 10V potential difference to a two 2ohm series circuit for example, both of the two 2ohm resistors will have 5V potential difference across them, resulting in a total of 10V. In this case the values of the resistors do not make any difference (two 5ohm resistances would result in the same voltage values), since we are not concerned with the current value (another subject).

If you have a 1 ohm and a 4 ohm resistance in paralled - if you need another example - , the voltage drop across the 1 ohm would be 2V while that across the 4 ohm would be 8ohms, for a total voltage value of 10 V again.

So, the if you study a circuit diagram, you will see that the voltage drops after the current of electrons (the current) passes through resistors. But, you have to be careful, the voltage drop is only porportional to the the ratio resistance value with respect to the total resistance value of the system, and for parallel resistors, the potential drop can only be calculated after calculating the combined resistance (another subject) of the resistors connected in parallel.

Therefore, changing a resistance will change the specific voltage drop across the resistance ONLY if there are more than one resistance in the circuit, since the drop depends on the proportion, not the resistance itself. Basically, it is the current that is changing.

The best way to understand the phenomenon is to understand the equation:

V=IR

where V is the potential difference, I is the current and R is the resistance.

PS. We are talking about a DC circuit, without alternating voltage, without inductances or capacitors, obviously.

Answer 2

If your power source is not designed to maintain the voltage, then the voltage will change somewhat, though mostly what you affect is current. Voltage is a difference in electrical potential between two points in a circuit -- if you have a battery supplying constant voltage on one side and a load on the other end that starts at zero electrical potential (because it's not running), adding a resistor in the line won't make the battery supply more voltage any more than it can make the load drop below zero electrical potential. Think of it like water in a hose. The city provides your water at around 60 psi, and generally, this doesn't change much. On the end of your hose, you have a spray nozzle with a certain amount of restriction to it, providing a certain resistance to flow. Now you put a kink in the hose -- adding more resistance. The pressure from the city doesn't change, but the amount of flow through your hose does. The overall pressure potential is the same -- 60 psi at the source, atmospheric pressure at the end of the spray nozzle, but now the inlet of the spray nozzle sees less than 60 psi due to the kink you put in the hose. So it depends on whether you're talking about the entire circuit or only the part that is "downstream" of the added resistance.

Answer 3

Can't really answer the first part without knowing the situation - how's it wired up?

2nd part: The voltage at one end of a resister will be different from the voltage at the other by I*R, the current through the resistor times the value of the resistor.

p.s. Grelann's discussion needs one change: in the 5th paragraph, change paralled to series.

Answer 4

potential difference is not the driving force of electrons. the term is electromotive force, or emf which is a term applied to electric source.

pd is a term for a load (a resistance).

pd=emf only when the there is only 1 load in the circuit. in this case increasing the emf of the supply will increase the pd across the load directly and equally.

increasing the resistance of the load does not increase the pd across it as the pd is dependent only on the emf applied. what actually changes is the current and this change follows ohm's law.

these statements are based on the assumption that there is only 1 load in the electrical circuit, the 1 whose resistance is the subject. and that the electrical supply has negligible internal resistance.