EMS 2

Question 1

State the difference between an AC waveform and a DC waveform

Answer 1

– Direct Current (DC)
In a DC circuit electrons flow in only one direction
– Alternating Current (AC)
In an AC circuit the electron flow periodically changes direction

Question 2

Define Frequency

Answer 2

The number of complete cycles of a periodic waveform occurring per second.
Frequency (f) is measured in Hertz (Hz).

Question 3

Define Wavelength

Answer 3

The distance between two points, at the same phase, in consecutive cycles of a waveform.
Wavelength (λ)is measured in meters (m).

Question 4

Define Amplitude

Answer 4

The distance of half the vertical extent of a waveform.
Also termed the peak value.

Question 5

Define Decibels (dB)

Answer 5

Decibels are defined as a convenient way to express power ratios as either
a gain or a loss.
* Decibels are logarithmic. i.e. Large changes in a power ratio produce a
small change in the dB value
* Decibels must be referenced to a power level to be useful e.g. 30dBmW
means that the power output is 1000 times more than 1mW

Question 6

List characteristics of a Wave

Answer 6