Average Power in an AC current.

In summary, the average power in an Alternating Current (AC) circuit with effective voltage V and effective current, I, is given by VI.
  • #1
wakejosh
102
0

Homework Statement


The average power in an Alternating Current (AC) circuit with effective voltage V and effective current, I, is given by which of the following? (Note: effective and RMS are the same)
a. 0.5 x VI b. VI c. 2.0 x VI d. 4.0 x VI e. V2I


The Attempt at a Solution




I understand that P=VI in this situation, so I am pretty sure the answer is B. the numbers up there are making me nervous. Just looking for a double check, thanks in advance.
 
Physics news on Phys.org
  • #2
You are right. Effective voltage and effective current can be regarded as the dc voltage and current which would produce the same power.
 
  • #3


Yes, you are correct. The average power in an AC circuit is given by P=VI, where V and I are the effective values (also known as RMS values) of voltage and current. The options provided are just different ways of expressing this formula, but the correct answer is b. VI. The other options may be used in other contexts or calculations, but for finding the average power in an AC circuit, the formula P=VI is the most appropriate.
 

1. What is average power in an AC current?

Average power in an AC current is the amount of power that is delivered or consumed by an electrical circuit over a period of time. It is calculated by taking the average of the instantaneous power values over one cycle of the alternating current.

2. How is average power different from instantaneous power?

Average power takes into account the entire cycle of an AC current, while instantaneous power only considers the power at a specific moment in time. This is because AC current fluctuates over time, causing the instantaneous power to vary, while average power remains constant over one cycle.

3. What is the formula for calculating average power in an AC current?

The formula for average power in an AC current is P=Vrms*Irms*cos(θ), where Vrms is the root mean square voltage, Irms is the root mean square current, and θ is the phase angle between the voltage and current. Alternatively, it can also be calculated as the product of the RMS values of voltage and current, P=Vrms*Irms.

4. How is average power affected by the phase angle between voltage and current?

The phase angle between voltage and current can affect the value of average power. If the phase angle is 0°, the average power will be at its maximum value. However, if the phase angle is 90°, the average power will be 0, meaning there is no transfer of energy from the source to the load.

5. Why is it important to calculate average power in an AC current?

Calculating average power in an AC current is important because it helps determine the efficiency of an electrical circuit. It also allows us to accurately measure the amount of power being consumed by a device or transmitted through a circuit, which is crucial for managing energy usage and preventing overload or damage to the system.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
492
  • Introductory Physics Homework Help
Replies
9
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Electrical Engineering
Replies
15
Views
486
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
2K
Back
Top