Glossary
Charge
A fundamental property of matter that causes it to experience a force when placed in an electromagnetic field.
Example:
An electron carries a negative charge, which is why it's attracted to a positively charged proton.
Conductors
Materials that allow electric charge to move freely through them, typically metals.
Example:
Copper wires are excellent conductors because their electrons are loosely bound and can flow easily.
Conservation (Conservation Laws)
Fundamental principles stating that certain physical quantities, like energy or charge, remain constant in a closed system over time.
Example:
The total momentum of a system of colliding billiard balls remains constant, illustrating the principle of momentum conservation.
Conservation of Charge
A fundamental principle stating that the total electric charge in an isolated system remains constant; charge cannot be created or destroyed, only transferred.
Example:
If a charged object touches a neutral object, the total charge before and after contact remains the same, demonstrating the conservation of charge.
Contact (charging method)
A method of charging objects by direct physical touch, allowing charge to transfer from a charged object to a neutral one.
Example:
Touching a charged metal sphere to a neutral one will charge the neutral sphere by contact.
Coulomb's Law
A fundamental law that quantifies the magnitude of the electrostatic force between two point charges, directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
Example:
Using Coulomb's Law, we can calculate the exact force of repulsion between two protons separated by a given distance.
Coulomb's constant (k)
A proportionality constant in Coulomb's Law that relates the electrostatic force to the magnitudes of charges and the distance between them.
Example:
The value of Coulomb's constant (k) is approximately 8.99 x 10^9 N·m²/C², a crucial factor in electrostatic calculations.
Coulombs (C)
The SI unit of electric charge, representing a large quantity of charge.
Example:
A typical lightning bolt can transfer several coulombs (C) of charge.
Electrostatic Force
The attractive or repulsive force between two charged objects, governed by Coulomb's Law.
Example:
The electrostatic force causes a positively charged ion to be pulled towards a negatively charged plate.
Electrostatics
The branch of physics that deals with the phenomena arising from stationary electric charges and their interactions.
Example:
Understanding electrostatics is crucial for explaining why dust sticks to a television screen or how a Van de Graaff generator works.
Elementary charges (e)
The smallest indivisible unit of electric charge, equal to the magnitude of the charge of a single proton or electron.
Example:
A single electron carries a charge of -1 elementary charge (e).
Fields
Regions in space where a force would be exerted on an appropriate object, used to predict and describe interactions without direct contact.
Example:
The Earth creates a gravitational field around it, which is why objects fall towards its surface.
Force Interactions
The fundamental ways in which objects or systems exert pushes or pulls on each other, characterized by magnitude and direction.
Example:
The attraction between a magnet and a paperclip is an example of a force interaction.
Friction (charging method)
A method of charging objects by rubbing them together, causing electrons to transfer from one object to the other.
Example:
Rubbing a balloon on your hair uses friction to transfer electrons, giving the balloon a static charge.
Induction (charging method)
A method of charging an object without direct contact, by bringing a charged object nearby to cause charge separation and then grounding the object.
Example:
A charged rod brought near an electroscope can cause its leaves to spread apart through induction, even without touching it.
Insulators
Materials that restrict or prevent the free movement of electric charge, such as rubber or plastic.
Example:
The plastic coating on electrical wires acts as an insulator to prevent electric shock.
Law of Electrostatics
A fundamental principle stating that like electric charges repel each other, and opposite electric charges attract each other.
Example:
According to the Law of Electrostatics, two positively charged balloons will push away from each other.
Negative charge
One of two types of electric charge, typically associated with electrons.
Example:
A balloon rubbed on hair gains a negative charge, allowing it to stick to a wall.
Newton's 3rd Law
A law stating that for every action, there is an equal and opposite reaction; applied to electrostatic forces, it means the force exerted by charge A on charge B is equal in magnitude and opposite in direction to the force exerted by charge B on charge A.
Example:
When a positively charged particle repels another positive particle, the force on the first particle is equal in magnitude and opposite in direction to the force on the second, illustrating Newton's 3rd Law.
Point charges
Idealized objects that have electric charge but are considered to have no physical size or dimensions.
Example:
When calculating the force between two distant charged spheres, they can often be approximated as point charges.
Positive charge
One of two types of electric charge, typically associated with protons.
Example:
A glass rod rubbed with silk acquires a positive charge.
Vector addition
The process of combining two or more vectors (quantities with both magnitude and direction) to find a single resultant vector.
Example:
To find the net electrostatic force on a charge due to multiple other charges, you must use vector addition to sum all individual forces.