https://www.youtube.com/watch?v=UyRv8bNDvq4

1
Water droplets orbiting charged darning needle
https//www.youtube.com/watch?vUyRv8bNDvq4
2
A flat circular ring is made from a very thin
sheet of metal. Charge Q is uniformly distributed
over the ring. Assuming w ?? R, the surface
charge density ? is

• Q/(2?Rw).
• Q/(4?Rw).
• Q/(?R2).
• Q/(2?R2).
• Q/(?Rw).

3
Three points inside a parallel-plate capacitor
are marked. Which is true?

• E1 ? E2 ? E3
• E1 ? E2 ? E3
• E1 ? E2 ? E3
• E1 ? E3 ? E2

Slide 26-67
4
If an electric dipole is place somewhere above an
infinite non-conducting plane with surface charge
sigma, then the net force on the dipole is always
zero, no matter the orientation of the dipole.

• True
• False

Slide 26-67
5
If an electric dipole is place somewhere above an
infinite non-conducting plane with surface charge
sigma, then the net torque on the dipole is
always zero, no matter the orientation of the
dipole.

• True
• False

Slide 26-67
6
If a non-conducting sphere with uniform charge
density ?gt 0 is placed above an infinite
non-conducting plane with density ?, the total
force on the sphere can be calculated as if the
sphere was a point particle at its center with
charge equal to the charge of the sphere.

• True
• False

Slide 26-67
7
A proton is moving to the right in a vertical
electric field. A very short time later, the
protons velocity is
8
Which electric field is responsible for the
protons trajectory?
A.
B.
C.
D.
E.