Electric Charge and Electric Force - AP Physics C: Electricity and Magnetism

The net force is the vector sum of individual forces. Multiple forces add vectorially to produce net force.

Newton per Coulomb (N/C). Equivalent to volts per meter (V/m).

Zero. Free charges redistribute to cancel internal fields.

Uniform field. Electric field is constant between infinite parallel plates.

$V = Ed$. For uniform fields, potential difference equals field times distance.

$Q = 20 \text{ C}$. Using $Q = CV = 2 \times 10 = 20$ C.

Charge resides on the surface. Charges move to the surface in electrostatic equilibrium.

+1.$602 \times 10^{-19} \text{ C}$. Equal magnitude but opposite sign to electron charge.

$F = 10 \text{ N}$. Using $F = qE = 2 \times 5 = 10$ N.

The total electric charge in an isolated system remains constant. Charge cannot be created or destroyed, only transferred.

$W = 5 \text{ J}$. Work equals charge times potential difference: $W = qV = 1 \times 5$.

$V = k \frac{q}{r}$. Potential decreases linearly with distance from the charge.

Electric charge is a property of matter that causes it to experience a force in an electric field. Fundamental property that creates electromagnetic interactions.

$5 \text{ V}$. Potentials add algebraically in series: $2 + 3 = 5$ V.

A conductor allows the flow of electric charge. Free electrons can move easily through the material.

$U = k \frac{q_1 q_2}{r}$. Energy stored in the configuration of two separated charges.

$8.99 \times 10^9 \text{ N m}^2/\text{C}^2$. Also equals $\frac{1}{4\pi\epsilon_0}$, the electrostatic constant.

Radially inward. Negative charges attract field lines toward them.

$E = \frac{F}{q}$. Electric field is force per unit charge.

$U = 4.495 \times 10^{9} \text{ J}$. Using $U = k\frac{q_1 q_2}{r} = 8.99 \times 10^9 \times \frac{1 \times 1}{2}$.

Uniform field. Electric field is constant between infinite parallel plates.

$V = Ed$. For uniform fields, potential difference equals field times distance.

Electric potential is the work done per unit charge in bringing a charge from infinity to a point in space. Energy required to assemble a charge configuration from infinity.

Radially outward. Positive charges create field lines pointing away from them.

$E = 1.8 \times 10^{10} \text{ N/C}$. Using $E = k\frac{q}{r^2} = 8.99 \times 10^9 \times \frac{2}{1^2}$.

$8.85 \times 10^{-12} \text{ C}^2/(\text{N m}^2)$. Also written as $\epsilon_0$, relates to Coulomb's constant.

$E = -\nabla V$. Electric field is the negative gradient of potential.

$E = k \frac{|q|}{r^2}$. Field decreases with the square of distance from the charge.

An insulator is a material that resists the flow of electric charge. Electrons are tightly bound and cannot move freely.