The figure belows shows two parallel plates. Assume they are infinite in area (t
ID: 1451637 • Letter: T
Question
The figure belows shows two parallel plates. Assume they are infinite in area (this way we can neglect edge effects). The plate on the left is at a potential of +28V and the plate on the right is at a potential of 0V. The plates are a distance 16cm apart and the dashed lines are spaced equally 4cm apart. Evaluate the following statements appropriately: The electric potential at point C is the electric potential at point A. The electric potential energy of a proton at point C is the electric potential energy of an proton at point A. The electric potential energy of an electron at point C is the electric potential energy of an electron at point A. The electric potential at point A is the electric potential at point D. What is the electric potential at point F? What is the magnitude of the electric Field at point A?Explanation / Answer
To solve these problems in electrical potential between parallel plates, we have expressions of potential.
V = - E d
Energy
U = q V
Part a )
The potential at the positive plate is +28 V and the negative plate is 0V, the potential decreases as we move from A -- C
The electric potential at point C is LESS than the potential at point A
Part b)
A proton has a charge
q = + 1.6 10-19 C
U = qV
UAC = + 1.6 10-19 ( VA – Vc)
as Vc <Va and the charge is positive
Uc < Ua
electric potential energy in point C is LESS than the electrical potential energy at point A
Part c)
q = - 1.6 10-19 C
UAC = -1.6 10-19 ( VA – Vc)
potential energy at point A potential Vc <Va, but the charge is negative to make the product is
Uc > Ua
electric potential energy in point C is GREATER than the electrical potential energy at point A
Part d)
As the two points are on the same line Va = Vd
The electric potential at point A is EQUAL to the electric potential at point D
Part e)
VF= V/4
VF = 28/4
VF = 7 V
Part f)
V = -E d
E = -V/d
E = - (0-28)/16 10-2
E = 1.75 102 V/m
E is constant between the two plates