HS-PS2 Electricity, magnetism and circuits
Aligned to HS-PS2 — Next Generation Science Standards.
What this lesson teaches
Electric charges create electric fields, and moving charges create magnetic fields, so electricity and magnetism are deeply linked. In a circuit, Ohm's law (V = I x R) relates voltage, current, and resistance. A changing magnetic field can push charges to flow, which is how generators produce electricity.
Worked examples
Example 1
A power plant spins a coil of wire inside a magnetic field; as the field through the coil changes, it induces a current, generating the electricity in your outlets. In a simple circuit with a 6-volt battery and a 2-ohm resistor, Ohm's law predicts a current of 3 amps (I = V / R).
Example 2
The induction only happens while the field is CHANGING. Hold the magnet still inside the coil and the current stops.
Example 3
Doubling the resistance halves the current at fixed voltage: I = V/R. That is why a thin wire heats and a thick one does not.
Practice questions
- State Ohm's law and define each variable.
- If a 12 V source drives a circuit with 4 ohms of resistance, calculate the current.
- Explain how a generator uses a changing magnetic field to make electricity.
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
HS-PS2 Electricidad, magnetismo y circuitos
Las cargas eléctricas crean campos eléctricos, y las cargas en movimiento crean campos magnéticos, por lo que la electricidad y el magnetismo están estrechamente relacionados. En un circuito, la ley de Ohm (V = I x R) relaciona el voltaje, la corriente y la resistencia. Un campo magnético cambiante puede impulsar el flujo de cargas, que es como los generadores producen electricidad.
Ejemplo 1: Una planta de energía hace girar una bobina de alambre dentro de un campo magnético; al cambiar el campo a través de la bobina, se induce una corriente que genera la electricidad que llega a tus contactos. En un circuito sencillo con una batería de 6 voltios y una resistencia de 2 ohms, la ley de Ohm predice una corriente de 3 amperes (I = V / R).
Ejemplo 2: La inducción solo ocurre mientras el campo CAMBIA. Deja el imán quieto dentro de la bobina y la corriente se detiene.
Ejemplo 3: Duplicar la resistencia reduce a la mitad la corriente a voltaje fijo: I = V/R. Por eso un cable delgado se calienta y uno grueso no.
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