Chapter 3

Answer 1

*

Question 2

What is amplitude?

Answer 2

A measurement of the amount of energy transferred by a wave

Question 3

What value does the voltage and current of a DC signal have?

Answer 3

A constant value

Question 4

What does the constant value of a DC signal make it?

Answer 4

Time-independent, meaning that it is not determined by the value of a variable representing time

Question 5

How does a variable representing time affect the voltage and current of a AC signal?

Answer 5

The voltage and current is time-varying, meaning that its amplitude changes with time

Question 6

What do AC signal generators create?

Answer 6

Produces sinusoids (i.e. sine
and cosine waves), triangular, and square waveform

Question 7

What are the uses of AC voltages?

Answer 7

They are easy to generate, transport across long distances and convert to and
from high voltages using transformers

Question 8

What are transformers?

Answer 8

A device that steps up (increase voltage, decrease current) or steps down (decrease voltage, increase current) voltage. Whilst keeping the input and output power the same

Question 9

What happens to energy at high voltages?

Answer 9

At high voltages, less energy is lost in electrical power transmission. Higher voltages mean lower currents, this results in less heat generated in the power line due to resistance.

Question 10

How can AC be converted to DC?

Answer 10

Using rectifiers

Question 11

What is periodic time (T)?

Answer 11

The time taken for one complete cycle of oscillation

Question 12

What is frequency (f) and its unit?

Answer 12

The number of oscillations or cycles in one second
unit is hertz

Question 13

What is the relationship between periodic time and frequency?

Answer 13

inversely proportional T = 1/f

Question 14

The frequency equivalent of periodic time 20ms?

Answer 14

1/0.02 = 50 Hz

Question 15

Equation for sinusoidal waveforms

Answer 15

v(t) = V sin (ωt + θ)
or
v(t) = V sin (2 π f t + θ)

Question 16

What are the parts in this equation v(t) = V sin (2 π f t + θ)?

Answer 16

v(t) - instantaneous voltage
V - peak amplitude voltage
ω - angular frequency
f - frequency
t - time (s)
θ - phase angle

Question 17

What is angular frequency (ω) and its unit?

Answer 17

ω = 2πf
Unit is radians per second or rad/s

Question 18

What is peak value of a signal?

Answer 18

The maximum value, either positive or negative that a waveform attains

Example;