• Stove Element
• Glassware: Pyrex and Corning Cookware

Stove Element

How does a stove work?

A stove is an appliance used to generate heat. Also known as ranges, modern gas and electric stoves are designed specifically to cook food. A typical electric range consists of heating units on the top surface called elements. They are composed of flat, coiled metal tubes that are made of nichrome-alloy resistance wires sealed inside stainless steel sheaths.

Electric current passes through the wires and generates heat that radiates out of the heating elements. This is shown when the coils turn bright red. Adjusting the voltage through the wires controls different heat settings.

Similarly, the elements in a ceramic or glasstop stove heat up in much the same way. The only difference is that the heating elements are covered by a smooth, glass-ceramic surface, hence are easier to clean.

How does the element heat up?

1. When the control knob is at off position, the cam presses its slimmest part on a lever spring. The lever spring then pushes up the contact arm spring with a maximum force, pivoting the contact arm left to open the circuit. The cam lets the springs push hard enough to hold the contacts apart despite the attraction of a magnet.


2. As the knob turns, the fatter parts of the cam bear on the lever spring, decreasing the leverage. The magnet overcomes the spring, closing the contacts to the heating element, letting the current flow through the heating coil around the bimetallic strip (which is heating and warping slightly). The strip bends the arm against the magnetic attraction, adding more separating force to the spring leverage.


3. When the knob is set to high position, the thickest part of the cam bears on the lever spring, pressing it down so that it exerts no leverage at all on the contact arm. The magnet holds the contacts together, as the bimetallic strip exerts separating force. The strip bends, the element stays on and reaches the highest temperature.

Glassware: Pyrex and Corning Cookware

Which types of glassware can be placed in an oven? Why?

There are various types of cooking vessels that can be placed in a regular oven, depending on the thermal conductivity of the material.

Glass is defined as an amorphous substance consisting primarily of fused silica with borates and phosphates. It is neither solid nor liquid but exists in a vitreous or glassy state. The atoms in glass, although arranged at random, are frozen in position. Glass by itself cannot be placed in an oven because it has a high melting point, therefore not permitting shrinkage or expansion with temperature changes. However, both Pyrex and Corning are derived from glass and consist of a slight change in chemical composition which allows it to be placed in an oven.

Pyrex is a borosilicate glass that contains borax as a major ingredient, along with silica and alkali. As alkali fluxes lower the fusion (or melting) temperature of silica, it gives way to shrinkage and expansion, consequently allowing it to be utilized in an oven. It is also noted for its durability and resistance to high temperatures, as it has a heightened thermal conductivity.

Corning is a glass-ceramic and is four or five times stronger and mechanically harder than glass. Glass containing certain metals will form a localized crystallization when exposed to ultraviolet radiation. If heated to high temperatures, the glass will convert to crystalline ceramics with mechanical strength and electrical insulating properties greater than that of ordinary glass. These properties allow Corning to be used in cooking.