Math Problem Statement

The power at a phase angle of 30° is 30 watts. What is the maximum power?

Solution

To solve this problem, we need to use the relationship between the instantaneous power and the phase angle in an AC circuit.

The formula for power at a phase angle is: P=Pmaxcos2(θ)P = P_{\text{max}} \cos^2(\theta) where:

  • PP is the power at a specific phase angle.
  • PmaxP_{\text{max}} is the maximum power.
  • θ\theta is the phase angle.

Here, P=30P = 30 W and θ=30\theta = 30^\circ.

Step 1: Rewrite the equation for PmaxP_{\text{max}}:

Pmax=Pcos2(θ)P_{\text{max}} = \frac{P}{\cos^2(\theta)}

Step 2: Compute cos(30)\cos(30^\circ):

cos(30)=32\cos(30^\circ) = \frac{\sqrt{3}}{2} cos2(30)=(32)2=34\cos^2(30^\circ) = \left(\frac{\sqrt{3}}{2}\right)^2 = \frac{3}{4}

Step 3: Substitute values into the equation:

Pmax=3034=30×43=40W.P_{\text{max}} = \frac{30}{\frac{3}{4}} = 30 \times \frac{4}{3} = 40 \, \text{W}.

Final Answer:

The maximum power (PmaxP_{\text{max}}) is 40 watts.


Would you like more details about this calculation or related concepts?

Related Questions:

  1. What is the general formula for power in an AC circuit with resistive and reactive components?
  2. How does the phase angle affect power in a circuit with inductors and capacitors?
  3. What is the significance of the maximum power in AC circuits?
  4. How can we derive cos(30)\cos(30^\circ) geometrically or algebraically?
  5. What happens to power if the phase angle changes to 6060^\circ?

Tip:

When working with AC power calculations, always double-check trigonometric identities and their squared values for precise results.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
AC Power Calculations
Phase Angle Relationships

Formulas

P = P_max * cos^2(θ)
P_max = P / cos^2(θ)

Theorems

Trigonometric Power Relationship
Cosine Function Squared

Suitable Grade Level

Grade 10-12