# Homework Help: Determine the base unit for the magnetic flux

1. Feb 22, 2009

### aaron86

1. The problem statement, all variables and given/known data
The e.m.f E of a battery is given by $$E = \frac{P}{I}$$ where P is the power supplied from the battery when current I flows through it. An e.m.f. $${E_c}$$ can also be induced in a coil when the magnetic flux, $$\Phi$$, associated with it changes with time, t, as expressed by $${E_c} = \frac{{d\Phi }}{{dx}}$$. Determine the base unit for the magnetic flux.

Answer is $$kg{m^2}{A^{ - 1}}{s^{ - 2}}$$

2. Relevant equations
$$E = \frac{P}{I} = \frac{{kg{m^2}{s^{ - 2}}}}{{A \cdot s}}$$

3. The attempt at a solution
I tried to integrate $$E = \frac{P}{I} = \frac{{kg{m^2}{s^{ - 2}}}}{{A \cdot s}}$$ but was stuck at getting the answer. Please help
Thanks!

2. Feb 22, 2009

There is no need to integrate,just rearrange your equation to make phi the subject then insert the base units and tidy it up.

3. Feb 22, 2009

### rl.bhat

Power = workXtime= kg*m^2*s^-3
flux = Pxs/I.
Now find the final unit.

4. Feb 22, 2009

Flux=Px/I.You have the right units for P,x is s and I is A

5. Feb 22, 2009

### aaron86

Thanks for the replies, however, aren't we suppose to extract information that is provided by the question?

How do you guys deduce the answer from $${E_c} = \frac{{d\Phi }}{{dx}}$$ ?

6. Feb 22, 2009