Quiz: Do you know how fluorescent lights work?



4 Min Quiz

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About This Quiz

Let there be fluorescent light! Fluorescent lights are found everywhere, but do you know how they work? Those white tubes are more efficient than incandescent bulbs and don't get as hot. Take our quiz to see how much you know about the science inside these fluorescent lamps.

Light energy is made up of small particlelike packets that have __________.

Light is a form of energy that is released by an atom. It consists of many small particlelike packets that have energy and momentum but no mass.


A light particle that has energy is called what?

The most basic units of light are photons, which are released from atoms when their electrons become excited.


When does a photon get released from an atom?

An excited electron holds its position for just a fraction of a second, then is drawn back toward the nucleus to its original orbit. As it returns to its original orbit, the electron releases extra energy in the form of a photon.


What is the main difference between the different types of light bulbs?

In an ordinary incandescent light bulb, atoms are excited by heat. In a light stick, atoms are excited by a chemical reaction. Fluorescent lights have a much more complex system for exciting atoms.


Which metal is contained in the sealed glass tube of a fluorescent light?

The sealed tube contains a tiny bit of mercury and an inert gas, commonly argon.


What happens when a fluorescent lamp is turned on?

When you turn on a fluorescent lamp, the current flows through the electrodes, which starts the movement of electrons from one end of the tube to the other.


Electrons from mercury atoms mostly release light photons from which wavelength?

The electrons in mercury atoms mostly release photons in the ultraviolet wavelength range. Human eyes cannot see ultraviolet photons, so they must be converted to visible light.


Ultraviolet light is converted to visible light by what part of the fluorescent lamp?

The inner part of the sealed tube contains a phosphor powder coating. Phosphors emit light in the visible spectrum when they are exposed to ultraviolet light energy.


Why are fluorescent bulbs more energy-efficient than incandescent bulbs?

Incandescent light bulbs emit quite a bit of ultraviolet light, which is not converted to visible light, and they also emit more heat than fluorescent lamps, losing more energy in the process.


Fluorescent lamps are how many times more efficient than incandescent lamps?

Although a typical fluorescent lamp is four to six times more efficient than an incandescent lamp, most people still use incandescent lights because they emit a "warmer" light.


What are ions?

Ions are atoms that have lost or gained an electron. These charged atoms are drawn to oppositely charged areas, just like electrons.


A fluorescent lamp needs what two things to send a current through the gas in the tube?

In a gas, an electrical charge is carried by free electrons or ions when there is a difference in charge between the two ends of the tube, i.e. voltage.


Which of these is a gas discharge lamp, which releases colored visible light when stimulated by ions and electrons?

Neon lights are gas discharge lamps that release colored visible light. Many street lights use a similar system with different gases.


What happens inside a fluorescent lamp when it's turned on?

There are few ions and free electrons in a gas, so the first thing a fluorescent lamp needs to do is release many new free electrons from both electrodes.


What is inside the casing of a conventional fluorescent starter switch?

The conventional starter switch has a small gas discharge bulb, which boils off electrons from a metal surface and sends them into the main tube and ionizes the gas inside.


What is the problem with the older conventional fluorescent starter switches?

Older fluorescent lamps take a few seconds to light up because the conventional starter switches take a few seconds to create enough ionizing gas for the main tube to start glowing.


Instant-start fluorescent lamps apply a very high initial voltage to the electrodes, which creates a _________.

A high initial voltage across the electrodes causes an excess of electrons on the electrode, with some electrons moving into the gas of the tube. This process, known as a corona discharge, ionizes the gas and sets off the electrical arc that lights the tube.


In terms of conducting electricity, what is a major difference between solids and gases?

In a gas discharge circuit, such as a fluorescent lamp, electric current causes resistance to decrease. This is because as more electrons and ions flow through a particular area, they bump into more atoms, which frees up electrons and creates more charged particles.


What part of a fluorescent light prevents an uncontrolled current from blowing out various electrical parts?

The simplest sort of ballast, a magnetic ballast, works like an inductor. It consists of a wire coil in a circuit, wound around a piece of metal, that works by opposing a change in the current flowing through it.


Which of these is NOT caused by magnetic ballasts?

Magnetic ballasts limit the electrical current at a low cycle rate, which can cause the light to flicker and also results in the humming sound that you might associate with older fluorescent lamps.


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