# Homework Help: I want to know about electricity.i am facing a huge difficulty in it.

1. Jun 7, 2013

### Shashank tekri

helo i am facing difficulty in understanding a question, help is required.
does the resistor affect the current flowing in a circuit if yes why and if no why.

2. Jun 7, 2013

### bhillyard

Look at it this way:
A resistor acts to alter the movement of electrons through the material.
The movement of electrons is the current.
So the resistance affects the current.

In mathematical terms the resistance is the voltage divided by the current - a three way relationship so varying one value will mean one or both of the other terms must also change.

3. Jun 7, 2013

A useful analogy for understanding why a resistor impedes current is the following:

Imagine you have balls rolling down a smooth hill (potential difference), and they will roll down this hill as quick as possible if there is nothing in the way. However, imagine now that the hill is covered in thick grass (resistor), and now their motion is slowed down by the obstacle in their way. So, a resistor can be thought of as an obstacle for that the electrons have to overcome, and thus cause their motion to slow down. Hope that helps; it's always useful to find analogies when learning new material.

4. Jun 8, 2013

### CWatters

The water analogy isn't perfect but... Think of a resistor as a restriction in a water pipe. The smaller the hole in the restriction the greater the resistance to water flow.

If the pipe with restriction is connected to a water source, one that provides constant water pressure (=voltage), then the greater the resistance..

1) the less water flows through it.
2) the greater the pressure (voltage) drop across the restriction.