THINGS AROUND US
5. Why do remotes work when we smack them?
Unfortunately, real life doesn't have a remote control. -Simone Elkeles
Have you ever wondered how do remote works magically when you hit it or smake it? I hope it is a common practice in Indian families. It happens most of the time but not all the time. This is no magic but there is an interesting scientific explanation for this physical phenomenon. Anyone can understand this thing if know some technical terms and concepts before explanation.
What is a remote?
In literal meaning, the word remote means "far apart" or "in distance" (generally far away). The literal meaning actually goes well with its use if you think for a minute. So technically a remote is an electronic device that uses radio waves(mostly) to operate an associated device from a distance. Historically remotes were made for war and military use but till Philco's mystery remote the remort controls were wired. This was the first battery-operated low-frequency radio-emitting remote.
Cell and battery
The modern-day remotes require a cell or a battery depending upon their use. Basically, a battery is a collection of connected cells. So, a cell and a battery is kind of similar thing from the inside.
A cell is an electro-chemical device that is capable of generating electric energy (current) from a chemical reaction. Then what is a chemical reaction? To put it in simple words when two or more chemical substances are kept to gather there will be some exchange of electrons provided the chemicals should be chosen in such a way that the exchange can take place. Fro now this is enough about chemical reactions.
As we use an AAA or AA battery for the remotes it is good to understand what happens inside it to produce electrical energy or the required voltage. These are dry cell battery means all the components are dry and can easily be transported. These are also called alkaline cells because this battery contains earth minerals like zinc, magnesium, graphite, or carbon. For a battery to work two things should take place. oxidation and reduction.
Oxidation: As the name suggests oxidation means that, when there is a reaction between oxygen and another element oxidation takes place. In general, oxygen is added to the other element. For example, rust is the result of the oxidation reaction between atmospheric oxygen, moisture, and iron. The resulting molecule is cammed as oxide. Most of the oxide feels like rust in terms of physical appearance but in different colors.
Reduction: Reduction means "reducing oxygen". So it is the opposite of oxidation.
Mostly oxidation and reduction take place momentously. So that there is a transfer of electrons which will produce chemical energy. This is how a battery works (This is not a very detailed explanation, but this is what happens in an overview).
Wetting current
Wetting current is the minimum electric current needing to flow through a contact to break through the surface film resistance at a contact (from Wikipedia). This means that if there is a barrier like an oxide film between the battery and a wire there is a minimum current that should be applied in order to establish a flow of current.
Why do remotes work when we smack them?
As we have all the background details we can proceed with the magical phenomena. When the batteries become old, due to the chemical process happening inside, there will be a very small amount of leakage and the battery are static which means they do not have any motion so over time a small oxide film or oxide layer is formed between the contacts of the battery. This oxide film acts as a barrier for the current to pass through them, as the battery does not produce much current to break the oxide the connection between the battery and the rest of the circuit is broken they the remote does not operate. Now when you smack or shake your remote there is a sudden movement and some impact so this will either break the oxide film or this will reposition the battery so that the connection is established again.
An interesting thing to note in your TV or AC remote.
The modern remotes use an IR LED to transmit the signals. The IR signals are not visible to our eyes but if you point your remote to your camera and press the buttons you will find a blink from the IR LED (like line normal LED)in violet color. Check it for yourself.
