The learning activities in this Lesson will help students prepare to complete the GE Lighting Auditor for their school or home as they learn about different types of light bulbs and how we light our world.

This Lesson comprises three learning activities.

Ways We Create Light is a Read About that discusses how incandescent, fluorescent, laser, and LED lights work. For more information on related concepts, see More Background included in this Lesson Plan.

Types of Light Bulbs is a Read About that describes the different types of incandescent, fluorescent, and high-intensity discharge (HID) light bulbs and their uses. For more information on related concepts, see More Background included in this Lesson Plan.

In Completing a Circuit,a Hands-on activity, students learn how to create an electrical circuit using simple materials to light a flashlight bulb.

• to describe different types of lighting, including natural light sources.
• that most light bulbs are either incandescent or fluorescent.
• to identify types of light bulbs.

The chart below suggests options for incorporating the activities into your schedule.

The two main types of light bulbs commonly found in indoor situations are incandescent and fluorescent.

Incandescent bulbs are used in most household lamps and light fixtures. Incandescent means to "glow with heat." Incandescent light bulbs consist of a hot wire in a bottle. The wire or filament must be a poor conductor of electricity. That way, it really heats up as electricity tries to go through it. The filament then glows. Interestingly, less than 10 percent of the electricity used actually produces light. The rest is what it takes to heat up the filament.

The filament does not burn up because of the vacuum, the lack of oxygen, in the bulb. The light eventually burns out because of the wear of electric current going through it. As the filament "burns," pieces of it blacken and collect inside the bulb, dimming the bulb.

Halogen bulbs are an unusual incandescent light. Halogen is a type of gas inside the glass. The bulb stays bright because of the "halogen cycle." During the halogen cycle, the filament pieces don't collect in the bulb. Instead, the tungsten filament reacts with the gas, which in turn deposits the tungsten back onto the filament. This process makes the bulb last longer, burn brighter, and stay bright the entire time.

Fluorescent bulbs are generally used indoors for offices, stores, and schools. Fluorescent means to "convert absorbed light into another form of light." The word comes from the mineral fluorspar, which glows from this process. Fluorescent lights work with ballasts and chemicals in the bulb. The ballasts are electrodes, or electrical conductors. The glass tube has a ballast at each end. When switched on, electricity flows to the ballasts, heating them. An electric current passes through the tube in an arc between the ballasts. The heat from the electricity vaporizes drops of mercury in the tube, making them emit ultraviolet light. Ultraviolet light is not visible to the human eye. But it still stimulates the coating of phosphor on the inside of the glass. It is the phosphor that makes the bulb shine in all directions.

Fluorescent bulbs cannot be made as small as incandescent lights can. New developments, however, have helped companies create smaller fluorescent bulbs. These new "compact fluorescents" can be used in most household fixtures that are on for long periods of time. Although the bulbs are more expensive than incandescent bulbs, their efficiency and longer life actually saves the consumer money.