Main Difference – Gravity vs. Electromagnetism
Gravity and electromagnetism are two of the four fundamental forces in physics. Out of the four fundamental forces, these two are most familiar to us. The main difference between gravity and electromagnetism is that gravity is a force between masses whereas electromagnetism is a force between charges.
What is Gravity
Gravity refers to the force of attraction between masses. It is one of the four fundamental forces, responsible for objects on Earth always falling down, for The Moon’s motion around The Earth, and The Earth’s motion around The Sun. It was Sir Isaac Newton who first managed to describe gravity mathematically when he realized that the motion of an apple falling from a tree and the motion of The Moon around The Earth are both due to an attraction between those objects and The Earth. His law of gravitation states that if two objects having masses and are separated by a distance , the gravitational attraction between them is given by:
Where is the universal gravitational constant . Later, Einstein’s work showed that Newton’s theory of gravity was incomplete. Today, gravity is explained using Einstein’s theory of general relativity. In Einstein’s theory, gravity is described as a curvature of space-time.
Out of the four fundamental forces, gravity is the most difficult force to unify with the other three types of forces. It is also comparatively much weaker compared to the other three types (the strong force, the weak force and electromagnetism).
What is Electromagnetism
Electromagnetism is the force that exists between charges. Electrostatic forces may exist between charges which are at rest, and when charges move, they may create magnetic fields around themselves. So, moving charges may exert electrostatic forces as well as magnetic forces between each other. If a particle with a charge is moving with a velocity through a region that has an electric field with strength and a magnetic field with strength , then the force on the particle is given by:
Electromagnetism is responsible for electricity and the attraction between magnets. It is also responsible, at a subtle level, for keeping you on a chair without you falling through it. Under the Standard Model of particle physics, electromagnetism is described as being mediated by particles called photons.
Difference Between Gravity and Electromagnetism
What they act on
Gravity acts on masses.
Electromagnetism acts on charges.
Electromagnetism is about 1035 times stronger than gravity .
Nature of Interaction
Gravity is always attractive.
Electromagnetism can be attractive or repulsive.
It is possible to shield spaces from electromagnetic forces.
There is no way to shield spaces from gravitational forces.
- Hughes, S. (2005, February 1). Introduction; Couloumb’s law; Superposition; Electric energy. Retrieved November 03, 2015, from MIT – Massachusetts Institute of Technology