1. Consider the Helmholtz coils, which have 130 turns per coil.Suppose that their
diameter is 2Rcoi1 = 0.304 m. Calculate the resulting magneticfield per ampere of
current, expressing your answer in units of milliTesla perAmpere.
2. Suppose that you apply a current of 1.5 Amperes through theHelmholtz coils.
Calculate the magnetic field, in milliTesla.
3. Suppose that the electrons are accelerated by a potential V =250 Volt, and they then
move in the magnetic field that you calculated in the previousstep. If the electrons
have the accepted value of elm = 1.76 x lOll [C/kg], what will bethe radius of the
circular orbit that they make?
4. In the' experiment, you will measure r, the radius of theelectron orbit, and you will
compute B, for various values of the current I flowing through theHelmholtz coils. _
You will then make a plot, with l/r2 on the vertical axis and B2 onthe horizontal axis.
The data points will fall mainly on a straight line of slope Q. Tofind elm from this
plot, you will need an expression for elm, in terms of the slope Qof this graph. Your
pre-lab question is to use Eq. (7.5) to find this expression.Please express it in the
forn1 elm = .... , where the expression on the right-hand-sideshould include the slope
a of the plot.
1. Consider the Helmholtz coils, which have 130 turns per coil.Suppose that their
diameter is 2Rcoi1 = 0.304 m. Calculate the resulting magneticfield per ampere of
current, expressing your answer in units of milliTesla perAmpere.
2. Suppose that you apply a current of 1.5 Amperes through theHelmholtz coils.
Calculate the magnetic field, in milliTesla.
3. Suppose that the electrons are accelerated by a potential V =250 Volt, and they then
move in the magnetic field that you calculated in the previousstep. If the electrons
have the accepted value of elm = 1.76 x lOll [C/kg], what will bethe radius of the
circular orbit that they make?
4. In the' experiment, you will measure r, the radius of theelectron orbit, and you will
compute B, for various values of the current I flowing through theHelmholtz coils. _
You will then make a plot, with l/r2 on the vertical axis and B2 onthe horizontal axis.
The data points will fall mainly on a straight line of slope Q. Tofind elm from this
plot, you will need an expression for elm, in terms of the slope Qof this graph. Your
pre-lab question is to use Eq. (7.5) to find this expression.Please express it in the
forn1 elm = .... , where the expression on the right-hand-sideshould include the slope
a of the plot.
