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Potential Energy

Potential Energy

The energy stored by a structure and location of matter in space is called potential energy. For instance, raising a kettlebell changes its spatial location and increases its potential energy. Similarly, a stretched rubber band contains potential energy which, under certain conditions, can be converted into other forms of energy, such as kinetic energy.
Chemical bonds that form attractive forces between atoms also contain potential energy, called chemical energy. When a chemical reaction...

Light as Energy

Light as Energy

The energy required to carry out photosynthesis is light— typically electromagnetic radiation from the sun. The range of all possible wavelengths is known as the electromagnetic spectrum.
Photons
A photon is a discrete electromagnetic particle or bundle of energy. Photons are characterized by their frequency, wavelength, and amplitude, similar to the properties of a wave. Waves with higher frequencies transmit more energy and have shorter wavelengths than longer wavelengths that transmit less...

What is Energy?

What is Energy?

The universe is composed of matter in different forms, and all forms of matter contain energy. The different forms of energy on Earth originate from the Sun — the ultimate energy source. Plants capture light energy from the Sun, and, via the process of photosynthesis, convert it into chemical energy. This stored energy from plants can be harnessed in many ways. For example, eating plant products as food provides energy for our body to function, and burning wood or coal (fossilized plants)...

Energy Carried By Electromagnetic Waves

Energy Carried By Electromagnetic Waves

Anyone who has used a microwave oven knows there is energy in electromagnetic waves. Sometimes, this energy is obvious, such as in the summer sun's warmth. At other times, it is subtle, such as the unfelt energy of gamma rays, which can destroy living cells. Electromagnetic waves bring energy into a system through their electric and magnetic fields. These fields can exert forces and move charges in the system and, thus, do work on them. However, there is energy in an electromagnetic wave,...

Energy Associated With a Charge Distribution

Energy Associated With a Charge Distribution

The work done to bring a charge through a distance r is given by the potential difference between the initial and the final position. To assemble a collection of point charges, the total work done can be expressed in terms of the product of each pair of charges divided by their separation distance, defined with respect to a suitable origin. Solving this expression gives the energy stored in a point charge distribution.

Potential Energy

Potential Energy

A conservative force, such as a gravitational or elastic force, gives the body the capacity to do work. This capacity, measured as the potential energy, depends on the body's location or “position” relative to a fixed reference position or datum. The gravitational potential energy is considered zero at the reference point. Suppose a body is located at some vertical distance above a fixed horizontal reference or datum. In that case, the weight of the body has positive gravitational potential...

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Related Experiment Video

Updated: Jun 25, 2026

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

Published on: August 27, 2019

Throwing light on dark energy.

Robert P Kirshner¹

¹Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 01238, USA. kirshner@cfa.harvard.edu

Science (New York, N.Y.)

|June 21, 2003

Summary

This summary is machine-generated.

The universe's accelerating expansion is driven by dark energy. Ongoing research aims to determine if this dark energy is constant or evolving, challenging our understanding of gravity.

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Last Updated: Jun 25, 2026

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

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Area of Science:

Cosmology
Astrophysics

Background:

Supernova observations reveal the universe's expansion is accelerating.
This acceleration is attributed to a mysterious dark energy filling space.
Current estimates suggest the universe is 14 billion years old, with 30% matter and 70% dark energy.

Purpose of the Study:

To precisely trace the history of cosmic expansion.
To investigate the nature of dark energy: a cosmological constant or a time-varying component.
To address fundamental gaps in our understanding of gravity.

Main Methods:

Analysis of supernova observational data.
Integration of data from multiple observational programs.
High-precision measurements over extended time spans.

Main Results:

The universe's expansion is confirmed to be accelerating.
Dark energy constitutes the majority (70%) of the universe's energy density.
The universe's age is estimated at approximately 14 billion years.

Conclusions:

The nature of dark energy remains an enigma, impacting fundamental physics.
Further research is needed to distinguish between a constant or evolving dark energy.
These findings highlight significant gaps in our comprehension of gravitational theories.