Neon bulbs are used throughout the world as indicating lights. Other gases are available to produce bulbs with varying and dazzling colors. These bulbs indicate whether water is flowing from the water purification plant to our house or whether the water is pouring out all over Main St. They indicate whether the hand brake is on in our car and whether our gas tank is nearing empty. We rely on these kinds of bulbs for a variety of things, including denoting whether the power is on for this monitor you are looking at.
The neon bulb can be used as an alternative electroscope to determine electric charge. When one electrode of the bulb is brought into contact with an object that is charged, a flash occurs. The neon bulb contains two electrodes in a space filled with neon gas. The light inside the neon bulb occurs nearest the negatively charged electrode (or cathode). When the bulb is lit with the 9-V transistor batteries note that the side of the bulb that is lit is always the side connected to the negative voltage of the batteries. If you switch the battery leads, the side of the bulb that lights will also switch. The light will always occur near the negatively charged electrode whether the source of charge is from a battery or from static charge.
The voltage difference causes an electric field to form which accelerates the electrons released by the cathode (negative electrode). These fast electrons then collide with the neon gas in the bulb causing the neon atom to lose an electron (ionization) or to shift an electron to a higher energy state (excited state). When the excited electron decays to a lower energy state or when the positive neon atom collects a free electron, energy will be released by the neon atom in the form of a photon or light flash. This causes the the red-orange light characteristic of neon. The flash occurs nearest the negative electrode because that is where the neon atom is most likely excited.
The neon bulb can be used as an alternative electroscope to determine electric charge. When one electrode of the bulb is brought into contact with an object that is charged, a flash occurs. The neon bulb contains two electrodes in a space filled with neon gas. The light inside the neon bulb occurs nearest the negatively charged electrode (or cathode). When the bulb is lit with the 9-V transistor batteries note that the side of the bulb that is lit is always the side connected to the negative voltage of the batteries. If you switch the battery leads, the side of the bulb that lights will also switch. The light will always occur near the negatively charged electrode whether the source of charge is from a battery or from static charge.
The voltage difference causes an electric field to form which accelerates the electrons released by the cathode (negative electrode). These fast electrons then collide with the neon gas in the bulb causing the neon atom to lose an electron (ionization) or to shift an electron to a higher energy state (excited state). When the excited electron decays to a lower energy state or when the positive neon atom collects a free electron, energy will be released by the neon atom in the form of a photon or light flash. This causes the the red-orange light characteristic of neon. The flash occurs nearest the negative electrode because that is where the neon atom is most likely excited.
