Grades 6–8 · Machines
How does an electric oven keep a whole space hot?
An electric oven heats a space rather than just the bottom of a pan. Current flows through resistive heating elements, raising their temperature. The hot elements and warmed oven walls radiate energy toward food. Air warmed by the surfaces moves and transfers energy by convection; a fan assists that movement in a convection oven.
In the diagramAn oven combines heat transfer and feedbackIllustrative control snapshots · selected setting: 180°CControlSensorHeater on150°CRadiationMoving warm airFoodTray contact conducts heatThe sensor measures the oven, not every food’s center.
A pan or baking tray also transfers heat by conduction where it touches food. These routes work together, so air temperature alone does not describe every heat transfer. A surface facing a hot element can receive more radiation than a sheltered surface at the same air temperature.
A sensor monitors oven temperature, and a controller compares it with the selected setting. The controller cycles or modulates the heaters to replace heat lost through the walls, ventilation and an opened door. Temperature can rise and fall around the setting as the system responds. The control is measuring the oven environment, not the temperature at the center of every piece of food.
About this explanation
Starting knowledge: Recognize conduction, convection and radiation and understand a temperature sensor.
Sources
- Whirlpool — Understanding How Ovens Work to Cook Food
- Whirlpool — Oven Overheating: thermostat and temperature sensor
- OpenStax — University Physics Volume 2: Mechanisms of Heat Transfer