Electric Fields: Invisible Forces of Nature
- Sylvia Rose
- 2 days ago
- 4 min read
Electric fields surround charged particles, creating an attraction or repulsion. Opposites attract, and objects with the same type of charges repel. Electric fields are in and all around us, on Earth and in space.
An electric field is the region around a charged particle where other charged particles experience a force. Particles carry positive or negative charges, depending on their atomic structure.
An atom has a nucleus of positive protons and neutral neutrons. Negatively charged electrons orbit the nucleus, attracted by the electric field of the protons.
If the force of attraction becomes weak, electrons can jump around and may move to other atoms. If an atom loses electrons it becomes a positively charged ion. If it gains electrons, its charge is negative.
A planet has an electric field created by the internal dynamics of its atmosphere. Electric and magnetic fields are strongly interrelated, creating electromagnetic fields.
People have electric fields due to the presence of electrically charged particles in the human body. The fields arise from biological processes such as nerve impulses and heart activity.
The human body has its own magnetic field, produced by electric activity especially in the heart and brain. The heartbeat creates an electric current running through the body and to every cell. The electric current in the body generates a weak electromagnetic field.
Electric field strength varies with distance from the source charge. The further from a charged object, the weaker the electric field becomes.
Electric fields are active in many natural occurrences. In thunderstorms, clouds become charged due to collisions of water and ice crystals.
This produces large fields of static electricity. Lightning is the powerful discharge of accumulated ions, electrons and electromagnetic radiation.
At the atomic level electric fields influence how atoms bond to form molecules. They determine the stability and reactivity of different substances.
Plants use their electric fields. They emit weak, negatively charged fields, used for communication with other organisms, such as bees. Electrical fields and can shape their structure and growth.
Electric fields affect the development of plant organs. They can either hinder or promote root growth and influence the growth direction.
In space, electric fields affect charged particles. Applied forces change their motion and possibly paths.
Electric fields affect spacecraft behavior, potentially causing interference and dangerous electrostatic discharges. They contribute to formation of electromagnetic waves, important to phenomena like space weather.
Field Lines
Field lines indicate the direction of the force a positive test charge would feel in the field. The closer the lines, the stronger the electric field.
In a charged capacitor, field lines between plates are densely packed. This indicates a strong electric field capable of storing electrical energy.
Field lines follow specific rules.
They originate from positive charges and terminate on negative charges (or extend to infinity).
The density of the lines indicates the strength of the field. Closer lines mean a stronger field.
The lines never cross.
The direction of the line at any point indicates the direction of the force on a positive test charge at that point.
The electric field around a single positive charge radiates outward in all directions, represented by lines pointing away from the charge. Around a single negative charge, the lines point inward.
Defining the Electric Field
The electric field at a point is the force that would be exerted on a positive test charge if it were placed at that point, divided by the magnitude of that test charge.
"force that would be exerted...": The electric field indicates what would happen to another charged object introduced into its influence.
"...on a positive test charge...": A test charge is a tool to map the field. The charge is defined as positive. The direction of force on this test charge indicates the direction of the electric field.
"...divided by the magnitude of that test charge...": This normalization ensures the electric field is a property of the source charge, not the test charge. It also gives the electric field units of newtons per coulomb (N/C).
A coulomb is equal to the quantity of electricity conveyed in one second by a current of one ampere. One newton is the force required to accelerate a mass of one kilogram by one meter per second squared.
The formula to measure electric fields is
E = F/q
E represents electric field strength.
F is the force felt by a test charge.
q is the size of the charge.
This formula shows the electric field strength is directly proportional to the force experienced and inversely proportional to the charge itself. Electric field strength is expressed in volts per meter (V/m).
If a force of 10 newtons is experienced by a charge of 2 coulombs, the electric field strength is calculated as:
E = 10 N / 2 C = 5 V/m
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