Class 5

Question 2

What is Coulomb’s Law?

Answer 2

Fe = k Qq/r^2 where k = 9x10^9

Question 3

Can Fe (electrostatic force) be attractive or repulsive?

Answer 3

Yes

Question 4

Fe = ?

Answer 4

qE

Question 5

A positive charge experiences force in the _______ direction as the electric field, E

Answer 5

same

Question 6

A negative charge experiences force in the _______ direction as the electric field, E

Answer 6

opposite

Question 7

Electric field at a point distance r away from a source charge: E = ?

Answer 7

k Q/r^2

Question 8

Electric field points _____ from a positive charge and _____ a negative charge.

Answer 8

pos. charge = away from neg. charge = towards

Question 9

Strength of the electric field corresponds to the ________ of field lines.

Answer 9

Density

Question 10

How does the electric field and electric field lines relate?

Answer 10

The electric field at any point is tangent to the field line.

Question 11

What are the units for electric potential?

Answer 11

J/C = V

Question 12

What does change in electrical potential equal?

Answer 12

delta PEe = q(delta)phi = qV

Question 13

How do you calculate work done by electric potential?

Answer 13

W by e = -(delta)PEe

Question 14

Positive charges want to accelerate to regions of ______ electric potential

Answer 14

Lower

Question 15

Negative charges want to accelerate to regions of ________ electric potential

Answer 15

Higher

Question 16

What are capacitors?

Answer 16

Two conducting surfaces separated by an insulator (dielectric) that can store charge and energy.

Question 17

Capacitance (C) = ?

Answer 17

C = kappaEo A/d Eo = constant kappa = dielectric number which is a characteristic of different insulators

Question 18

What are the units of capacitance?

Answer 18

Farads, F

Question 19

In diagrams of batteries (two lines), which line is the positive terminal?

Answer 19

The longer of the two lines.

Question 20

When connected to a battery in a closed circuit, a capacitor will store charge: Q = ?

Answer 20

Q = CV

Question 21

How do you calculate the uniform electric field created between charges on capacitor plates?

Answer 21

E = V/d

Question 22

When a capacitor is charged, it is also storing energy: PEcap = ? = ? = ?

Answer 22

PEcap = 1/2QV = 1/2CV^2 = Q^2/2C

Question 23

How do you determine the stored energy in a capacitor using a Q vs V graph?

Answer 23

PE = area under curve

Question 24

What does a dielectric do and how does it affect capacitance (numerically)?

Answer 24

Increases capacitance according to its dielectric number, kappa: C = kappaC0