Solar Oven Science

Overview

The Solar Oven Science activity was developed as a way to target conservation of energy. Some students understand that he sun can be used for heating and cooking but they mistakenly think that this can only work in deserts. Because of conservation of energy solar cooking and heating can work in temperate and even arctic environments. The linked video shows solar oven working to make Smores at the South Pole!

Steps

Line the interior of a cardboard box with black paper. Line the flaps of the box with reflective material. Use tape more cardboard, or whatever innovative materials you need to get the flaps of the box to stay open around the opening of the box (see pictures.) Place the thermometer or sample in the box and cover with cling film. I have found it helpful to use a pushpin to stabilize the sample in the center of the box. Go outside with the box and aim the opening at the sun. You need to be directionally accurate here--aim at the sun and get rid of any shadows on the face of the box by aiming. Now wait.

Student designs are various and with more or less help they can come up with unique, self-designed products. The solar oven they make is authentic-you'll really go outside and measure what temperature the interior reaches using a thermometer and you can see the temperature increase if you use a sample of chocolate or similar inside the box. We even used bagel bites and they really did warm up.

How it works

The sun's radiant (light) energy is collected in a box with an absorbing, black interior. Additional rays are reflected into the box by various designs in which the flaps of a box are covered in reflective materials to aim more sun in. The radiant energy of the sun is transformed into thermal energy and the cling film helps to keep in the thermal energy. The dark color of paper absorbs the radiation instead of reflecting it.

Connections

• Make half of the boxes with black interiors and half with white interiors. Compare the results of the boxes with similar structures and different interior colors. Relate to the effects of melting icecaps and increasing water surface area of the world to talk about radiation absorbed by the earth which contributes to it's warming versus radiation reflected by snow and ice covered regions. Look at images of changing reflective surface areas.

• Use the solar oven cling film as a model for the earth's atmosphere which helps keep thermal energy in so we can have life on earth. The moon at a similar distance from the sun is considerably colder because it lacks an atmosphere (and a warm core but anyway.)) Talk about making the film thicker and maybe try solar ovens with thicker plastic or more layers of cling film.

• Ask students to predict whether this would work at the South Pole. Watch the video.