Question

Which type of waves are produced by a television remote controller?
A.)Infra-red waves
B.)Radio waves
C.)Ultraviolet waves
D.)Visible light

Answer 1

Hint: The remote control should use the light wave which has low energy but good range. The wavelength ranges from 700nm to 1mm. This value is ideal for remote-control communication. Some electromagnetic waves can also be dangerous for the human. body.

Complete step-by-step answer:
The electromagnetic spectrum goes as follows:
Gamma Rays → X-rays→ UV Rays→ Visible Light→ InfraRed→ Radio waves.
This order is in terms of increasing wavelength. As we move from left to right, the wavelength increases.
To determine the kind of electromagnetic wave that we use to transmit signals from remote control, we need to understand the properties first.

Infra-red waves are generated from the heat-bodies. This is a low energy wave with no apparent effect on the human body. The range of the Infrared light of low power can be 15-20 meters. It travels at the speed of light. So, this is perfect for communication between a remote control and TV/stereo.

The main drawback of using Radio waves is that the energy of the wave is too low. That is why the communication between the two electronic equipment might be hampered and discontinuous.

Ultraviolet waves are high energy electromagnetic waves, and it is often regarded as dangerous to humans. It can cause mutations and other problems. As there should be constant communication between the equipment, this will be very harmful for humans.

Visible light has its own problem because of interference. Visible light can be shielded easily and other light sources can interfere with the signal.

As a result, we can say that Infrared is the best choice for communication with a remote control. This is in fact the electromagnetic wave used.
So, the correct option is (A).

Note: Infrared waves are used in the remote control, but now it has been shifted to Wi-Fi. Wi-Fi is more convenient because of the range and connectivity of the remote control. You should approach this type of question with the options. Consider the properties of each option and discard it if it is not applicable. We have done the solution in a similar way.