A little agitation.
From an invisible field to a warmer meal.
See inside a microwave, then zoom in to the water molecules doing the absorbing.
An electric field becomes heat.
The magnetron generates microwaves. Metal walls contain the field, and the food absorbs some of its energy. Water molecules respond to the changing electric field; interactions within the material turn that energy into heat.
A bent water molecule has a negatively biased oxygen end and a positively biased hydrogen side. The field changes the tendency to orient; random thermal motion continues, including after the source stops. Alignment, jitter, and response lag are exaggerated for clarity; the bonds stay intact.
The field nudges.
The material warms.
The field keeps reversing.
At 2.45 GHz, the electric field completes 2.45 billion cycles each second. Water’s molecular dipoles feel a torque as its direction changes.
The response loses energy to the surroundings.
In condensed food, molecules interact with their neighbors and respond with a lag. Dielectric loss transfers energy from the field into disordered molecular motion. Dissolved ions can also contribute to heating.
Heat spreads through the food.
A higher temperature means greater average thermal energy. Uneven absorption creates hot and cold regions; turning the food changes what each region experiences, while heat flows between neighboring regions.
Model, timescales & energy balance
Illustrative water-like food: heat capacity 4,180 J/(kg·K), 24 equal-mass regions, ambient 20 °C. The modeled load absorbs 65% of the 900 W source output when it is on. Turning redistributes a fixed total absorbed power across a chosen uneven field pattern; it does not change that total.
Neighbor heat exchange conserves energy. A small heat loss to the surroundings is included. Local temperature is limited to 100 °C; further input is tracked as a phase-change budget. Evaporation, changing mass, convection, and actual cooking chemistry are omitted. This is a teaching model, not a cooking-time prediction.
Heating and the 6 rpm turntable run at 4× time. The displayed molecular field cycle is slowed independently to 0.65 Hz; neither the drawn oscillations nor molecular positions are to scale. Reduced-motion settings hold the drawings still while the heat calculation continues. Liquid water absorbs over a broad frequency range.