# Math Help - electric field.

1. ## electric field.

An electric field of 281,000 N/C points due west at a certain point. What are the magnitude and direction of the force that acts on a charge of -7.4 µC at this spot?

magnitude in Newtons
direction?

couldn't this be set up as: F = (-7.4uC) * (281,000 N/C)

is uC the same as C? just uC is a micro Coulomb?

also, do i need this expressed in scientific notation to make it correct.

2. Originally Posted by rcmango
An electric field of 281,000 N/C points due west at a certain point. What are the magnitude and direction of the force that acts on a charge of -7.4 µC at this spot?

magnitude in Newtons
direction?

couldn't this be set up as: F = (-7.4uC) * (281,000 N/C)

is uC the same as C? just uC is a micro Coulomb?

also, do i need this expressed in scientific notation to make it correct.
To get a force in units of newton you need to express -7.4uC as $-7.4 x 10^{-6}$ C, then do the multiplication. Giving the answer using scientific notation is probably the simplest way of giving it.

With the cancellation of powers of 10, it'll actually just be F = -7.4 x 0.281 N = ......

You should be able to the multiplication on paper - without a calculator

And you do realise that you 'lose' the minus once you give the direction ....?