Electromagnetic Waves (VSAQs)

Physics-2 | 11. Electromagnetic Waves – VSAQs:
Welcome to VSAQs in Chapter 11: Electromagnetic Waves. This page includes the important FAQs for Very Short Answer Questions. Answers are provided in simple English and follow the exam format. This will aid in concentrating on key concepts and achieving top marks in your final exams.

VSAQ-1 : Give any one use of infrared rays.

One use of infrared rays is in TV Remote Control. Infrared energy is employed in standard TV remote controls to transmit signals to the television. This technology enables users to change channels and control various functions from a distance, making it a convenient and common application in households.

VSAQ-2 : If the wavelength of electromagnetic radiation is doubled, what happens to the energy of photon?

When the wavelength of electromagnetic radiation is doubled, the energy of the photon decreases by half. This relationship is based on the fact that photon energy is directly proportional to its frequency and inversely proportional to its wavelength. Doubling the wavelength corresponds to halving the frequency, resulting in a reduction in photon energy.

VSAQ-3 : What are the applications of microwaves?

Microwaves are used in various applications:

  1. Cooking: Efficient heating in kitchen appliances.
  2. Communication: Key for mobile phones and Wi-Fi.
  3. Radar: Vital in aviation, maritime, and weather forecasting.
  4. Traffic Control: Used in fixed speed cameras.

VSAQ-4 : Microwaves are used in Radars, why?

Microwaves are used in radars due to their unique properties. Their high frequency and short wavelength allow them to bounce off objects and return to the radar receiver. By measuring the time, frequency shift, the radar can determine distance, speed, and motion of objects, making microwaves a crucial component in radar systems used for navigation, weather monitoring, and defense applications.

VSAQ-5 : How are microwaves produced?

Microwaves are produced using vacuum tube devices that manipulate electron motion with magnetic or electric fields. In microwave ovens, the chosen microwave frequency matches the resonant frequency of water molecules, allowing high-energy microwave photons to transfer their energy as kinetic energy to the water molecules. This increase in thermal energy effectively cooks and heats food in microwave ovens.

VSAQ-6 : What is sky wave propagation?

Sky wave propagation, also known as “skip,” is a type of radio wave propagation where radio waves are reflected or refracted back to Earth from the ionosphere, an electrically charged layer in the upper atmosphere. This phenomenon enables radio signals to cover long distances, making it valuable for long-range communication, including broadcasting and shortwave radio transmissions.

VSAQ-7 : The charging current for a capacitor is 0.6 A. What is the displacement current across its plates?

The displacement current across the plates of a capacitor is equal to the charging current. So, in this scenario, the displacement current is 0.6 A.