Question 259: Magnetism and Matter

Question

A 4.0 cm long straight wire carrying a current of 8 A is placed perpendicular to a uniform magnetic field of strength 0.15 T . The magnetic force on the wire is ________mN .

Accepted Answer

To calculate the magnetic force on a wire, we use the formula:
$ \mathrm{F} = \mathrm{I} \ell \mathrm{B} $
Where:
$ \mathrm{I} $ is the current in the wire (in amperes),
$ \ell $ is the length of the wire (in meters),
$\mathrm{B}$ is the magnetic field strength (in teslas).
Given that:
The current $\mathrm{I}$ is 8 A,
The length of the wire $\ell$ is 4.0 cm, which is 0.04 m (since 1 cm = 0.01 m),
The magnetic field strength $\mathrm{B}$ is 0.15 T,
Substituting these values into the formula gives:
$  \mathrm{F} = 8 	imes 0.04 	imes 0.15  $
Calculating this:
$  \mathrm{F} = 0.048 \, \mathrm{N}  $
To convert this to millinewtons (mN), recall that $1 \, \mathrm{N} = 1000 \, \mathrm{mN}$. Therefore:
$  \mathrm{F} = 48 \, \mathrm{mN}  $
Thus, the magnetic force on the wire is 48 mN.

Magnetism and Matter

A 4.0 cm long straight wire carrying a current of 8 A is placed perpendicular to a uniform magnetic field of strength 0.15 T . The magnetic force on the wire is ________mN .

Choose the correct answer: