# Practice Page

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### 503-F: Coulombs Law 1: Two charges

• Topic Cluster: Fundamental Forces
• Topic: Inverse Square Laws
• Objective: Numerically solve Coulomb's Law
• Content: The magnitude of the electrostatic force acting on two objects is proportional to their charges and inversely proportional to the square of the sitance between their centers of charge; the constant of proportionality is called the Coulomb's Law Constant.
• Level: 2

### Practice Page Available as a PDF

$$F_E = k \frac{q_1 q_2}{d^2}$$

Symbol
Quantity
SI Unit
$$F_E$$
Electrostatic Force
Newtons (N)
$$k$$
Coulomb's Constant = $$9.0 \cdot 10^9 \frac{\text{N} \cdot \text{m}^2}{\text{C}}$$
$$\frac{\text{N} \cdot \text{m}^2}{\text{C}}$$
$$q_1$$
Charge 1
Coulombs (C)
$$q_2$$
Charge 2
Coulombs (C)
$$d$$
Distance between charges
Meters (m)

#### Attraction and Repulsion

An electrostatic force can be either an attractive charge or a repulsive charge, depending upon the situation. Like charges repel each other, and opposite charges attract.

Charge
Attract or Repel?
Positive and Positive
Repulsive
Negative and Negative
Repulsive
Positive and Negative
Attractive

### Useful Constants

Symbol
Name
Value
Explanation
$$e$$
Elementary Charge
$$1.602 \cdot 10^{-19} \text{ Coulombs}$$
The charge of a single proton or electron.
angstrom
$$1 \cdot 10^{-10} \text{ meters}$$
A frequently used distance unit for the insides of atoms.