Answer:
The smallest integer is n = 4
Explanation:
Using the equation V= Sqrt(F/Linear density)
V= Sqrt(341/0.0120)
V= Sqrt(28416.7)
V= 168.57m/s
Path distance =[ (n +1)/2]lambda
But V= f(Lambda)
n lambda/2 =L
n = f2L/V
n = (20 × 2 × 16.86) / 168.57
n = 4.0007
The smallest integer is n= 4
Apparently, the question is looking for A. electric potential energy;
but I don't think that's quite right. Electric potential difference is expressed in Joules / Coulomb which is the work to move a charge between 2 points
Example: If the electric field between, say, between 2 capacitor plates is
E = 100 Newtons / Coulomb then the work done in moving a unit of charge from the negative plate to the positive plate separted by 1 cm is
V = E * d = 100 Newtons / Coulomb * .01 meters = 1 Newton-meter / Coulomb
= 1 Joule / Coulomb which is the electric potential or potential difference
(The definition of electric potential between points is "the work moving a unit positive test charge from one point to the other")
Now in our above example where V = 1 Joule / Coulomb
if we move 10 Coulombs from the negative plate to the positive plate
W = V Q = 1 Joule / Coulomb * 10 Coulombs = 10 Joules
where work done has the correct units of Joules.
Your textbook should help clarify this.
