Physics 2 Exam 2 HW 5

The electric field strength between two parallel conducting plates separated by 4.5 cm is 7.9 × 104 V/m.

What is the potential difference between the plates, in kilovolts?

delta V = Ed

Consider the parallel-plate capacitor shown in the figure. The plate separation is 3.4 mm and the the electric field inside is 26 N/C. An electron is positioned halfway between the plates and is given some initial velocity, vi.

What speed, in meters per second, must the electron have in order to make it to the negatively charged plate?

F = qE

F = ma

a = (qE)/m

**acceleration will be negative because it opposes acceleration within the field

vf^2 = vi^2 + 2ad

**d = 1/2d in this case

If the electron has half the speed needed to reach the negative plate, it will turn around and go towards the positive plate. What will its speed be, in meters per second, when it reaches the positive plate in this case?

vi,a = 1/2vi

vf,a = 0

vi,b = 0

vf,b = ?

vf,a^2 = vi,a^2 + 2ad,a

d,a = -vi,a^2/2a

dtot = d,a + 1/2d

vf,b^2 = vi,b^2 +2adtot

In the coordinate system shown at right, particle 1 with charge q1 = q, where q= 8.6 μC, is located at coordinates (-a, 0) m, where a = 2.2 m; particle 2 with charge q2 = 2q is located at coordinates (a, 0); particle 3 with charge q3 = q is located at coordinates (0, a).

Enter an expression for the electric potential at the origin, V0, using the given symbols.

V = (kq)/r or (kq)/a

V = (kq/a) + (2kq/a) + (kq/a)

V = (4kq)/a

A research-level Van de Graaff generator has a 2.25 m diameter metal sphere with a charge of 5.05 mC on it.

What is the potential near its surface in MV? (Assume the potential is equal to zero far away from the surface.)

V = (kq)/r

**r = 1/2d

At what distance in meters from its center is the potential 1.00 MV?

V = (kq)/r

r = (kq)/V

An oxygen atom with two missing electrons is released from rest near the Van de Graaff generator. What is its kinetic energy in MeV at the distance from part b?

K = 2(vi -vf)

Two point charges, Q1=Q2=+2.11μC, are fixed symmetrically on the x axis at x=±0.207m. A point particle of charge, Q3=+3.93μC, with mass m=11.9mg can move freely along the y axis.

If the particle on the y axis is released from rest at y1=0.0161m, what will be its speed, in meters per second, when it reaches y2=0.0719m? Consider electric forces only.

1/2mv^2 = 2k(q)(q3)I(1/sqrt x^2 + y2^2) - (1/sqrt x^2 + y1^2)I

Consider a parallel-plate capacitor made up of two conducting plates with dimensions 17 mm × 27 mm.

If the separation between the plates is 1.4 mm, what is the capacitance, in pF, between them?

C = (ε0A)/d

If there is 0.43 nC of charged stored on the positive plate, what is the potential, in volts, across the capacitor?

Q = CV

V = Q/C

What is the magnitude of the electric field, in newtons per coulomb, inside this capacitor?

E = V/d

Three capacitors are connected as shown in the figure, C1 = 2.4 μF, C2 = 10.8μF, C3 = 6.2 μF. The voltage on the battery is 12 V.

Calculate the numerical value of the total energy stored in the capacitors U, in microjoules.

U = 1/2Ceq(V^2)

A hollow conducting sphere has an inner radius of r1 = 1.2 cm and an outer radius of r2 = 3.2 cm. The sphere has a net charge of Q = 2.8 nC.

What is the magnitude of the field, in newtons per coulomb, at a distance r = 6.2 m away from the center of the sphere?

E = (kq)/r^2

Consider a parallel plate capacitor having plates of area 1.65 cm2 that are separated by 0.014 mm of neoprene rubber. You may assume the rubber has a dielectric constant κ = 6.7.

What is the capacitance in nanofarads?

C = (κε0A)/d

What charge, in coulombs, does the capacitor hold when 9.00 V is applied across it?

Q = CV