My question is how does metal corrosion affect a reed switch?
This question is from my textbook. We are following cambridge igcse science.
To understand how metal corrosion affects a reed switch, let's break it down step by step.
1. What is a reed switch?
A reed switch is an electrical switch that consists of two flexible metal prongs, called reeds, inside a sealed glass tube. The reeds are made of a ferromagnetic material, typically nickel-iron alloy, and have contacts at their ends. When a magnetic field is applied near the switch, the reeds attract and make contact, allowing electric current to flow.
2. What is metal corrosion?
Metal corrosion is the natural process of deterioration that occurs when a metal reacts with its environment. It usually happens due to chemical reactions with substances such as oxygen, moisture, acids, or salts. Corrosion can cause the metal to weaken, degrade, and eventually fail.
3. How does metal corrosion affect a reed switch?
If a reed switch is exposed to a corrosive environment, like high humidity or a presence of corrosive chemicals, it can lead to corrosion on the metal surfaces of the reeds. Corrosion can affect the overall performance and reliability of the reed switch in several ways:
a. Increased resistance: Corrosion can create a layer of non-conductive material on the reed's contacts, increasing the resistance of the switch. This can lead to faulty or intermittent operations and affect the switch's sensitivity to magnetic fields.
b. Sticking: Corrosion products can cause the reeds to stick together. This prevents the proper separation of the reeds when a magnetic field is removed, which can result in delayed response times or complete failure of the switch.
c. Physical damage: In severe cases, corrosion can weaken the metal structure of the reeds, making them more prone to breakage and resulting in permanent damage to the switch.
4. How to mitigate the effects of metal corrosion on a reed switch?
To minimize the impact of metal corrosion on a reed switch, the following measures can be taken:
a. Use protective coatings: Applying protective coatings, such as anti-corrosion paints or sealants, to the reeds and other metal parts can reduce their exposure to corrosive substances.
b. Control the environment: Avoid exposing the reed switch to high humidity, moisture, or corrosive gases. Use appropriate housing or enclosures to shield the switch from potentially corrosive elements.
c. Regular maintenance: Inspect the reed switch periodically for signs of corrosion or damage. Cleaning the contacts with appropriate solutions or using contact cleaners can help remove corrosion buildup and maintain proper functioning.
By understanding the nature of metal corrosion and taking preventative measures, the negative effects on a reed switch can be minimized, ensuring its optimal performance and longevity.
Corrosion (an oxide layer) on the reed surfaces can cause the switch to not "close" when contact is made. This problem happens often, especially on battery contact terminals. I often have to remove and rub battery contact points on my TV receiver remote control, for a similar reason.
Corrosion on a time-delay startup reed relay switch of my stereo system kept causing one of the channels to go out. It had to be removed and cleaned. It also happens on the RV stereo system. Turning up the volume helps "sap" the odide layer ans re-establish electrical contact.