x Turn on thread page Beta
 You are Here: Home >< Physics

# Step up transformers - confusion watch

1. I know step up transformers decrease power loss by the electrical cables, but I'm not quite sure how this works....

From what I understand, step up transformers increase voltage, hence decrease current, which means less power is dissipated by the cables since P=(I^2)R.

But then couldn't you argue that since step up transformers increase voltage, then actually the power dissipated by the cables increases since P=(V^2)/R ??
2. (Original post by onnek)
I know step up transformers decrease power loss by the electrical cables, but I'm not quite sure how this works....

From what I understand, step up transformers increase voltage, hence decrease current, which means less power is dissipated by the cables since P=(I^2)R.

But then couldn't you argue that since step up transformers increase voltage, then actually the power dissipated by the cables increases since P=(V^2)/R ??
In the first formula, the current, I, is the current in the cables. Reducing this, for a particular value of R, the resistance in the cables, does indeed reduce the power loss in the cables.
In the second formula, V is not the voltage output from the transformer, V is the voltage drop along the cables. It's this voltage, across the cable resistance, that is the source of the lost power.
3. (Original post by onnek)
I know step up transformers decrease power loss by the electrical cables, but I'm not quite sure how this works....

From what I understand, step up transformers increase voltage, hence decrease current, which means less power is dissipated by the cables since P=(I^2)R.

But then couldn't you argue that since step up transformers increase voltage, then actually the power dissipated by the cables increases since P=(V^2)/R ??
the higher the voltage goes, the higher the resistance the current faces in the cables, the higher the resistance, the higher chance of power loss.

hopes this helps
4. (Original post by big-boss-91)
the higher the voltage goes, the higher the resistance the current faces in the cables, the higher the resistance, the higher chance of power loss.

hopes this helps
Noooo!

stonybridge is right
5. (Original post by Joinedup)
Noooo!

stonybridge is right
or go for stonybridge answer, looks right! its been years since GCSE physics for me haha!

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 12, 2011
Today on TSR

### Happy St Patrick's day!

How are you celebrating?

### Stay at sixth form or go to college?

Discussions on TSR

• Latest
Poll
Discussions on TSR

• Latest

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE