FINAL TERM EXAMINATION_ECE13_SY 2024-2025

What is the amount of voltage induced in a wave by an electromagnetic wave?

• Magnetic field

• Power density

• Receive voltage

• Field strength

In electromagnetic waves, polarization _________.

• Is caused by reflection

• Results from longitudinal nature of the waves

• Is always vertical in an isotropic medium

• Is due to the transverse nature of the waves

Electromagnetic waves are refracted when they ______________.

• Encounter a perfectly conducting surface

• Pass through a small slot in a conducting plane

• Pass into a medium of different dielectric constants

• Are polarized at right angles to the direction of propagation.

What is the thickest layer of the ionosphere?

• D

• E

• F1

• F2

The layer that reflects very low frequency waves and absorbs medium frequency waves.

• D

• E

• F1

• F2

What layer is used for high-frequency daytime propagation?

• D

• E

• F1

• F2

What is the highest frequency that can be sent straight upwards and be returned to earth?

• MUF

• Critical frequency

• Skip frequency

• Gyro frequency

If the transmitter power remains constant, an increase in the frequency of the sky wave will

• Lengthen the skip distance

• Increase the range of the ground wave

• Reduce the length of the skip distance

• Have no effect on the ground wave range

What is a wavefront?

• A voltage pulse in a conductor

• A fixed point in an electromagnetic wave

• A current in a conductor

• A voltage pulse across a resistor

A mobile receiver experiences 'dead' areas of reception as a result of

• Atmospheric absorption

• Shading of the RF signal by hills and trees

• Tropospheric scatter

• Sporadic E