# Homework Help: Graph of V and I against time in AC

1. May 12, 2006

### al_201314

While revising on A.C, I came across the graph of V and I across a resistor plotted against time on the same axis. The book is Serway's College Physics 7th edition. Both curves are sinosoidal and are in phase which I understand, but why does the curve of I is always at a higher amplitude than V? As I know, V = IR, wouldn't the voltage curve have a higher amplitude, that is the peak value of voltage would correspond to a lower peak current for a given resistor? Why in this case is it the other way round?

Thanks for any inputs.

2. May 12, 2006

### Cyrus

look at the units on that scale. They are not the same. Your question is meaningless. You will see what I mean once you figure out the solution.

Last edited: May 12, 2006
3. May 12, 2006

### Curious3141

As Cyrus said, when different units are plotted on the same axis, comparison is meaningless without a scale.

But even if the axis is specifically drawn such that 1A (one ampere) and 1V (one volt) have the same segment length on the vertical axis, the I curve can be higher than the V curve. Think about what happens when you have a resistance that is less than one ohm.