# Calculating Frequency.

1. Feb 10, 2010

### daveiejbeer

Hello my mind has gone blanc whilst in the middle of my AC Theory assignment.
The question is:
Calculate the frequencies for the following wave forms:
i. An alternating current that completes 4 cycles in 5ms
ii. An alternating current that completes 5 cycles in 8ms.

Am I right in thinking work out how many ms to complete 1 cycle then work out using f = 1/T

Can anyone point me in the right direction?

Dave

2. Feb 10, 2010

### tiny-tim

Welcome to PF!

Hello Dave! Welcome to PF!
Yup!

Well … sort-of … if it's 1 cycle in T milliseconds, then it's 1000 cycles in T seconds, so it's … ?

3. Feb 10, 2010

### thebigstar25

frequency is usually in Hz so you need first to convert the time from ms to s .. the second thing is that what you are thinking is right,but there is an even easier direct way .. Why just dont you say that the frequency (f) = no. Of cycles / time .. :) then you will have the problem done..

4. Feb 10, 2010

### rl.bhat

Hi daveiejbeer, welcome to PF.
Frequency f = no. of cycles per second.
In the first case convert ms to s and find f.

5. Feb 10, 2010

### daveiejbeer

Thanx for your help. I have already worked out the answers but I wasn't converting it into seconds, Doh!

Thanx once again.

Dave