Question

3. With regards to the discovery of magnetism and electricity, and the first scientific approach to understanding the laws of electronics, answer the following questions:

a) Discuss how early people considered the origin of ‘non-contact’ forces such as magnetic forces. Who did the first experiment to quantify the force between charged objects and when? [5 Marks]

b) Briefly explain Coulomb’s experiments. [8 Marks]

c) Explain the microscopic origin of the contact force. [7 Marks]

Answer 1

a) people Understood non contact forces very early since permanent magnets existed long before but it's scientific understanding with experiment came later around 18th century.

Many scientists have performed the experiment on non contact forces like electric force, magnetic force, gravitational force.

Initially experiments were performed on charge particles which attract each other without coming into contact. Charles Augustin de couolmb was first who successfully verified the force of attraction and repulsion between unlike and like charges in 1785.

Later Cavendish verified the force of attraction between two massive objects known as gravitational force in 1798.

After that many experiments are performed to verify magnetic forces also.

b) couolmb law is an experimental law that verifies the force between two stationary charged particle.

c) force arises from interaction between two bodies.
By contact forces we mean the forces which are transmitted between bodies by
short-range atomic or molecular interactions.
Examples: push, pull, tension of a string, normal force, the force of friction, etc.

Consider now tiny mattress structure. When a force acts downwards on the floor, the floor distorts slightly and the floor structure becomes compressed. The reaction to being compressed provides an upward force to support the gravity force and this upward force is often referred to as the reaction force from the surface (the floor in this case). It is an example of a compression force: something is compressed and exerts a force as a result of this compression.