Forces and Energy in Fields
Aligned to HS-PS3-5 — Next Generation Science Standards.
What this lesson teaches
Objects can push or pull each other without touching through electric and magnetic fields. As two objects move within a field, the force between them changes and so does the stored potential energy. Moving them apart or together against the force stores or releases energy.
Worked example
Push two north poles of magnets toward each other and you feel the repulsion grow as they get closer. You are doing work against the field, and that work is stored as magnetic potential energy. Release them and that stored energy converts back into kinetic energy as they fly apart.
Practice questions
- State what happens to the force between two like charges as they are brought closer together.
- Two magnets attract from 10 cm apart. Describe how the force and the stored potential energy change as they move to 2 cm apart.
- Draw a field diagram for two opposite charges and mark where potential energy is lowest, explaining your choice.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Fuerzas y Energía en los Campos
Los objetos pueden empujarse o atraerse sin tocarse a través de campos eléctricos y magnéticos. A medida que dos objetos se mueven dentro de un campo, la fuerza entre ellos cambia y también lo hace la energía potencial almacenada. Separarlos o acercarlos en contra de la fuerza almacena o libera energía.
Ejemplo: Empuja dos polos norte de imanes uno hacia el otro y sentirás crecer la repulsión conforme se acercan. Estás realizando trabajo en contra del campo, y ese trabajo se almacena como energía potencial magnética. Suéltalos y esa energía almacenada se convierte de nuevo en energía cinética al separarse rápidamente.
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