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What is the meaning of resistance?

Physics Asked on March 31, 2021

I am a 10th grade student and I have a little trouble in knowing what is resistance?

I know this might be a silly question for others but My thinking of resistance is that it opposes the flow of charges/Current but I want to know that why the current remains the same even after passing through a resistance, If it is opposing the current , then it should get decreases, I know there is no charge storing device in between so the charges cannot be accumulate so, the current should remain same but then what’s the point of resistance? If the charge flow is same everywhere why do we talk of resistance?

I mean suppose that if I have" i "amount of current going through two resistors separately one of them have resistance R and other at 2R ,do we mean that the charges will cross the resistance R in more time than 2R?But the rate of flow of charges inside the two resistors separately stays constant? But I don’t think so? because the current is same when it pass through both resistors separately so , same no. of charges will cross in same time so,I think that they will cross it in the same time.

please explain by giving as many examples as possible because its my first time I am reading about current and electricity so, I don’t know much about it. I also don’t think that the speed of current will decrease? suppose if I have a less resistance does it mean that current will pass through it in less time? I don’t think so, I have that feel of resistance that it is opposing the flow and increasing the temperature, but I don’t know the exact meaning of resistance?

2 Answers

The voltage across the resistor drops. The current cannot due to conservation of charge.

the current should remain same but then what's the point of resistance?

This is not to say that a resistor has no effect on the current. In fact the current (electrons) is actually slowed down as it passes through the resistor. But the number of electrons entering the resistor is the same as the number of electrons exiting it.

If the charge flow is same everywhere why do we talk of resistance?

Because in designing electrical circuits we are concerned with the ease/lack-of with which something will let electricity flow through it. A conductor has low resistance, while an insulator has much higher resistance. Resistors let us introduce precisely controlled amounts of resistance into electrical circuits which is very helpful in designing such circuits.

Answered by joseph h on March 31, 2021

In the hydraulic analogy, resistance is like putting rocks in the pipe. It takes more effort (= pressure = voltage) to push water at high speed through rocks than through an empty pipe, even though the water leaves that section of pipe at the same rate that it enters whether the rocks are there or not.

Answered by benrg on March 31, 2021

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