# Help with symbols Ø and ∆

1. Sep 1, 2011

### MattVonFat

Hi,

I'm doing a physics home study course and in the text it says:

It hasn't mentioned what the symbols Ø and ∆ mean before so I figure it's something I was expected to have known.

I'd really appreciate it if someone could help me out with this.

Thanks,
Matt

2. Sep 1, 2011

### bp_psy

Ø is used for the empty set and I think they should have use ∆Q not ØQ.
∆ is used to denote a finite amount of something:∆t-some amount of time, ∆x some distance in the x direction,∆Q some charge.