Wireless Communication

The ratio of the amplitude of the magnetic field to the amplitude of the electric field for electromagnetic wave propagation in a vacuum is equal to

• Unity

• Speed of light in vacuum

• Reciprocal of the speed of light in vacuum

• The ratio of magnetic permeability to electrical susceptibility in a vacuum.

Which properties amount the following is false about electromagnetic waves?

• The energy in an electromagnetic wave is divided equally between electric and magnetic vectors.

• Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of the wave.

• These waves do not require any material medium for propagation

• Both electric and magnetic field vectors attain the maxima and minima at the same place and the same time

Which property of an electromagnetic wave, depends on the medium in which it is travelling?

• Velocity

• Frequency

• Wavelength

• Time period

Answer explanation

The frequency, wavelength and time period can all vary according to the wave producing source. But, the velocity of an electromagnetic wave depends upon the medium through which it is travelling. The velocity of wave in a vacuum is termed as speed of light, which is assumed to be 3 x 10⁸ m/s.

Electromagnetic waves are represented in which of the following format?

• Longitudinal waves

• Transverse waves

• Sinusoidal waves

• Surface waves

Answer explanation

Explanation: A sinusoidal wave describes the oscillation periodically. Since the electromagnetic wave is represented in the form of sine curve it is named after it as sinusoidal wave.

For increasing accuracy, high frequency of propagation is used.

• TRUE

• FALSE

Answer explanation

Explanation: In order to increase accuracy, it is recommended to use an extremely high frequency of propagation. However, the available phase comparison techniques cannot be used at frequencies greater than 5* Hz, which corresponds to a wavelength of 0.6 m.

Energy of the discrete particles can be given by

• Photons

• Protoplasm

• Electrons

• Neutrons

Answer explanation

Explanation: Photons act as a constituent particle in case of electromagnetic wave. These possess certain properties like energy and momentum which is able to deliver it to the wave and helps in certain classifications.

Which among the following is having more wavelengths?

• X-rays

• Cosmic waves

• Radio waves

• Gamma rays

Answer explanation

Explanation: Radio waves possess the longest wavelength in the electromagnetic spectrum, which makes it suitable in the usage of classified radars for operating in a particular region.

Which of the following indicates the correct set of combination in radio waves?

• Shorter wavelength – high frequency

• Longer wavelength – less frequency

• Shorter wavelength – less frequency

• Longer wavelength – high frequency

Answer explanation

Explanation: From the relation it can be clearly seen that wavelength and frequency are inversely proportional to each other which makes it form a relation that is shorter wavelength must possess high frequency which makes it suitable in case of cosmic rays and radio waves.

EM waves varies from ______ to ________

• Meters to nano-meters

• Meters to micro-meters

• Nano to micro-meters

• Centimeters to nano-meters

Answer explanation

Explanation: The EM wave is continuum of energy, which under goes certain propagations. During this course, it may undergo some undulations which result in decrease of the wave length capacity. Generally, these vary from meters to nano-meters.

The formula of energy produced from the body can be given as _________

• Q = h- c / λ

• Q = h*c * λ

• Q = h+ c / λ

• Q = h*c / λ

Answer explanation

Explanation: The energy propagated from the body can be determined byQ = h*c / λ. From this, the wave length can be determined by having an energy value. This help in the determination of the wavelength by using plank’s constant.