Coulomb
Definition
A coulomb is the unit of electric charge in the International System of Units (SI). It represents the amount of charge transported by a constant current of one ampere in one second.
Analogy
Imagine a coulomb as a bucket filled with electric charge. Just like you can measure how much water is in a bucket, a coulomb measures how much electric charge is present.
Key Equations
Coulomb's Law: [ F = k \frac{{|q_1q_2|}}{{r^2}} ]- (F) is the force between charges,
- (q_1) and (q_2) are the magnitudes of the charges,
- (r) is the distance between the centers of the two charges,
- (k) is Coulomb's constant ((8.987 \times 10^9 , \text{Nm}^2/\text{C}^2)).
Problem Solving Tips
- Always express charges in Coulombs and distances in meters to maintain consistency with the unit system.
- Remember that forces are vectors. When multiple charges are involved, vector addition may be needed to find the net force.
- Pay attention to the signs of the charges; like charges repel, and unlike charges attract.
Relevant Experiments
- Measuring the force between charged objects at varying distances gives empirical evidence supporting (F \propto 1/r^2). - Using charge sensors and force meters, one can quantify the relationship between charge magnitude, distance, and force, confirming Coulomb's Law. - Experiments using a torsion balance are classic methods to demonstrate Coulomb’s Law, similar to how Coulomb originally explored the law.
Related terms
Electric Field: The region around an electrically charged object where another charged object experiences an electric force.
Electric Potential Energy: The energy that an object possesses due to its position in an electric field.
Electric Force: The attractive or repulsive force between two charged objects.
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