Is it energy or power or neither?

In summary, the conversation discusses the characteristics of a power signal and the confusion surrounding a particular signal that has infinite energy but also gives an infinite power when calculated. The speaker learns that a power signal can have infinite power and that the signal they are discussing falls under this category. The conversation also mentions that there are signals that do not fit into either the energy or power type.
  • #1
FRANCLI
12
0
Is it energy or power or neither?!

Hi,
I found in one of my lectures that the signal x(t) which equals e to the power t, is a power signal but when I calculate its power it gives infinity?
So I'm asking it is really a power signal and I mad a mistake in my calculation or what?
Thanks in advance ..
FRANCLI :)
 
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  • #2


FRANCLI said:
Hi,
I found in one of my lectures that the signal x(t) which equals e to the power t, is a power signal but when I calculate its power it gives infinity?
So I'm asking it is really a power signal and I mad a mistake in my calculation or what?
Thanks in advance ..
FRANCLI :)

A power signal has infinite energy, and an energy signal has finite energy. You can remember this easily by recognizing that a signal with infinite energy can have a finite power (so it is sensible to measure its characteristics with power) and a signal with finite energy has ... finite energy (so it's a comfortable choice to measure its characteristics)

edit:
Also, a power signal can have finite power, but it does not need to as you have found out through calculation.
 
Last edited:
  • #3


OK, now this signal have infinite energy but as I said when I calculate its power it also gives me infinity:(
 
  • #4


FRANCLI said:
OK, now this signal have infinite energy but as I said when I calculate its power it also gives me infinity:(

The answer is infinity, and that is acceptable for a power signal.
 
  • #5


Oh, really :)
I didn't know that because my textbook said that the signal is a power signal if its power is between zero and infinity and there was no sign that the infinity value itself is acceptable.
 
  • #6


Can you show me your calculation step by step? You are probably wrong. The power of a signal x(t) is calculated by

Px = lim (T goes to inf) [(1/T) int (-T/2 to T/2) |x(t)|^2 dt].

So, the power of x(t)=e^t is zero. Hence, x(t)=e^t is a power signal since it has infinite enegry.

However, there exist signals that are neither energy type nor power type. One example of such signals is x(t)=e^t u(t), where u(t) is the unit step function. (quoted from contemporary communication systems).
 

1. What is the difference between energy and power?

Energy and power are often used interchangeably, but they are two distinct concepts. Energy is the ability to do work or cause change, while power is the rate at which energy is used or transferred. In other words, energy is the amount of work that can be done, whereas power is the speed at which that work is done.

2. Can something have energy without power?

Yes, something can have energy without power. For example, a battery may have a certain amount of energy stored in it, but it does not have any power until it is connected to a circuit and can do work. In this case, the energy is potential and becomes power when it is converted into kinetic energy.

3. Is it possible for something to have power without energy?

No, it is not possible for something to have power without energy. Power is a measure of the rate of energy transfer, so in order for something to have power, it must have energy to transfer. However, the amount of energy and power may vary depending on the system and its efficiency.

4. How are energy and power related to each other?

Energy and power are related to each other through the concept of work. Work is the transfer of energy, and power is the rate at which work is done. In other words, power is the energy per unit time. The greater the power, the faster energy is transferred.

5. Is it possible for something to have both energy and power?

Yes, it is possible for something to have both energy and power. For example, a moving car has both kinetic energy and power. The car's energy is the amount of work it can do if it were to collide with another object, while its power is the rate at which it is using that energy to move. In general, most systems have both energy and power, but the specific amounts of each may vary.

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