SP212 Lab: Three! Equipotential Surfaces and Electric Fields
Version: February 1, 2015
I. Procedure*
A. *Parallel*Plates*of*Charge*
a)
Set*the*two*straight*electrodes*up*as*shown*on*Graph*1:**Place*one*along*the*y*
=*1*inch*line*and*the*other*on*the*y*=*8*inch*line.**Place*the*electrodes*near*the*
left*side*of*the*tray,*leaving*plenty*of*space*on*the*right*side.***
b)
Pour*about*a*centimeter*of*water*in*your*water*tray.*
c)
Set*your*digital*function*generator*(DFG)*for*sinusoidal*output,*and*connect*a*
long,*black*banana*cable*to*ground,*or*“GND.”**Connect*a*long,*red*banana*
cable*to*“Hi*Ω.”**Make*sure*the*Amplitude*is*turned*all*the*way*down,*that*is,*
all*the*way*counterclockwise.****
d)
Connect*the*other*end*of*the*black*cable*to*the*y*=*1*inch*electrode,*so*that*will*
be*GND.***
e)
Connect*the*other*end*of*the*red*cable*to*the*y*=*8*inch*electrode.**
f)
Set*your*Protek*DMM*to*measure*AC*Volts;*that’s*the*“V”*with*the*tilde*(~)*
above*it.***
g)
Being*careful*not*to*move*the*electrodes,*connect*the*“GND”*terminal*of*your*
Protek*to*the*“GND”*electrode,*and*the*“V”*terminal*to*the*other*electrode. *
h)
Turn*on*the*Protek,*turn*on*the*DFG,*and*set*the*frequency*to*300*Hz.**
i)
Carefully*increase*the*DFG*amplitude*up*to*approximately*5.00*Volts*(the*DFG*
doesn’t*have*a*voltage*indicator,*so*we*must*use*the*protek),*as*nearly*as*you*
can.**Record*the*actual*value,*calling*it*Vmax.*
j)
Locate*and*trace*out*4*equipotential*surfaces*between*the*two*plates*and*
measure*the*distance*of*each*from*the*ground*plate.**Think*about*this*process.**
Will*it*be*easier*to*choose*integer*values*of*potential,*or*integer*values*of*
distance*from*the*grounded*plate?**
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Equipotentials and Electric Fields
Graph 1