The Big Misconception About Electricity

Veritasium・2 minutes read

A giant circuit with a battery, switch, and light bulb spanning 300,000-kilometer wires questions how quickly light illuminates after the switch is closed, showcasing energy transmission through electric and magnetic fields, not electron movement. The Poynting vector formula demonstrates energy flowing from the battery to the bulb almost instantly, emphasizing the significance of understanding energy flow through fields in circuits.

Insights

  • Energy in circuits flows through electric and magnetic fields, not the physical movement of electrons, as described by Maxwell's equations and the Poynting vector formula.
  • The light bulb in the giant circuit scenario would light up almost immediately, in approximately 1/C seconds, showcasing the rapid propagation of electric and magnetic fields through space.

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Recent questions

  • How does electricity flow in circuits?

    Electricity in circuits flows through electric and magnetic fields, not the movement of electrons. Energy is transmitted via these fields, as described by Maxwell's equations and the Poynting vector formula for energy flux.

  • What is the Poynting vector formula used for?

    The Poynting vector formula is used to show the flow of energy in circuits, from the battery to the light bulb, even in alternating current circuits. It describes the transmission of energy through electric and magnetic fields, rather than the movement of electrons.

  • What is the significance of understanding energy flow through fields?

    Understanding energy flow through electric and magnetic fields is crucial, as highlighted by issues faced by undersea telegraph cables due to signal distortions. Energy transmission through fields, not electron movement, plays a key role in efficient energy transfer in circuits.

  • How quickly does a light bulb light up in a circuit?

    In a circuit with a battery and light bulb, the light bulb would light up almost instantaneously, in roughly 1/C seconds. This rapid lighting is due to the propagation of electric and magnetic fields through space, rather than the physical movement of electrons.

  • Where can I find more information about Caseda's smart switch?

    More information about Caseda's smart switch can be found at lutron.com/veritasium. This smart switch can be connected with assistance available through a simple click or call, providing convenient and efficient control over lighting systems.

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Summary

00:00

Electricity Flows Instantly Through Fields

  • The giant circuit in the video includes a battery, a switch, a light bulb, and two 300,000-kilometer-long wires.
  • Light travels the distance of the wires in one second, reaching halfway to the moon and back to the light bulb one meter away.
  • The question posed is how long it takes for the bulb to light up after the switch is closed.
  • The electricity in power grids is in the form of alternating current (AC), with electrons wiggling back and forth without physically moving.
  • Energy is transmitted through electric and magnetic fields, not by the movement of electrons.
  • Maxwell's equations describe oscillating electric and magnetic fields in light, leading to the Poynting vector formula for energy flux.
  • In a circuit with a battery and light bulb, energy flows through the electric and magnetic fields, not the movement of electrons.
  • The Poynting vector shows energy flowing from the battery to the bulb, even in alternating current circuits.
  • Undersea telegraph cables faced issues due to distortions in signal transmission, highlighting the importance of understanding energy flow through fields.
  • The light bulb in the giant circuit question would light up almost instantaneously, in roughly 1/C seconds, due to the propagation of electric and magnetic fields through space.

14:32

"Caseda smart switch connects easily with assistance"

  • Caseda's smart switch can be connected with assistance available through a click or call.
  • Further information on Caseda can be found at lutron.com/veritasium.
  • Lutron Electronics sponsored the video, with appreciation extended to the viewers.
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