Basic Continuous Time Signals Concepts - Waveform Properties: Power and Energy Signals

Question 1

Define a power signal.

Answer 1

A power signal is one where 0 < P_x < ∞ and E_x → ∞

Question 2

Define an energy signal.

Answer 2

An energy signal is one where 0 < E_x < ∞ and P_x = 0

Question 3

What is the average power of a signal?

Answer 3

P_x = ∫ x(t)² dt

Question 4

What is the total energy of a signal?

Answer 4

E_x = ∫ x(t)² dt

Question 5

What characterizes a signal that is neither a power nor an energy signal?

Answer 5

P_x → ∞ and E_x → ∞

Question 6

How is the time constant τ related to exponential decay?

Answer 6

τ is the time it takes to fall to 37% of the initial value

Question 7

What does the impulse function δ(t) equal for t ≠ 0?

Answer 7

0

Question 8

What is the sampling property of the impulse function?

Answer 8

∫ x(t) δ(t - T) dt = x(T)

Question 9

True or False: An energy signal can have infinite power.

Answer 9

False

Question 10

Fill in the blank: A signal x(t) is classified as an energy signal if _______.

Answer 10

Question 11

Fill in the blank: A signal x(t) is classified as a power signal if _______.

Answer 11

0 < P_x < ∞

Question 12

What is the average of any signal x(t) defined as?

Answer 12

Question 13

Why is average not a good measure of a signal?

Answer 13

Because it may not reflect the signal’s size accurately

Question 14

What is the time constant for growing exponentials?

Answer 14

Time it takes to rise to 63% of the final value

Question 15

What are the conditions for a signal to be classified as an energy signal?

Answer 15

Must fit within a decaying envelope and not be zero for all t

Question 16

What happens to the power of a signal if it is periodic?

Answer 16

Average power is calculated over one period

Question 17

What is the relationship between power and energy for signals?

Answer 17

Energy signals have zero power, while power signals have infinite energy.

Question 18

True or False: Signals that ‘start’ and ‘stop’ in finite time can qualify as power signals.

Answer 18

False

Question 19

What is the significance of the term ‘average square’ concerning power signals?

Answer 19

It represents the average power of the signal

Question 20

What is an example of a signal that does not qualify as energy or power?

Answer 20

x(t) = 0

Signals with inifinite poer always have infinite energy

Question 21

How is the instantaneous power delivered to a resistor defined?

Answer 21

P_x = v(t) x(t)

Question 22

What does the term ‘average power’ refer to in the context of signals?

Answer 22

The average power delivered by a signal to a resistor over time

Question 23

Fill in the blank: For a signal to be classified as a power signal, it must not qualify as an energy signal and must fit in a _______.

Answer 23

power envelope

Question 24

What is the time constant τ always related to in exponential functions?

Answer 24

e^(-t/τ) reaching 37% of its starting value