Answer: Infrared.
- A Infrared
- B Radio waves
- C Visible light
- D Microwaves
Correct answer: A. Infrared
Explanation: TV remote controls use infrared LEDs (wavelength ~940 nm). The IR signal carries coded information (pulse patterns). The TV sensor detects these IR pulses.
In an electromagnetic wave, the oscillating electric field (E) and magnetic field (B) are perpendicular to each other and to the direction the wave travels - a purely transverse wave that needs no medium, unlike sound.
Concept context
Maxwell's equations, EM spectrum, properties, and applications of each band.