# Homework Help: Resistance of a cylindrical resistor

1. Aug 2, 2017

### Cici2017

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
Can someone tell me what formula to use? Is it p=RA/L? but what about the mass? Thanks~

2. Aug 2, 2017

### Dadface

What can you infer about the volume of the smaller resistors compared to the volume of the larger resistor?

3. Aug 2, 2017

### Cici2017

p=m/V ,

if m half, V half,

V=πr2L

right?

4. Aug 2, 2017

### epenguin

I will tell you don't use any formula. It will do you no good, maybe less than none. Use physical thinking. Use a thought experiment like slicing a resistor in two.

Get the physical understanding then that will help you understand the formula!

5. Aug 2, 2017

### Dadface

I agree with epenguin who has given you very good advice. If you do need to refer to a formula try to get a good understanding of what the formula is actually referring to. In many cases you will find it's common sense. Without understanding the formula you're just substituting numbers and probably learning very little.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted