Math Problem Statement

Alma is an electrical engineer who is testing the voltage of a circuit given a certain current and resistance. She uses the following formula to calculate voltage:

voltage = (current)⋅(resistance)

The circuit she tests has a current of 4 + j3 amps and a resistance of 5 – j3 ohms.

What is the voltage of the circuit?

Solution

To calculate the voltage VV of the circuit given the current II and resistance RR, we use the formula:

V=IRV = I \cdot R

Given:

  • Current I=4+j3I = 4 + j3 amps
  • Resistance R=5j3R = 5 - j3 ohms

We perform the multiplication of these two complex numbers:

(4+j3)(5j3)(4 + j3) \cdot (5 - j3)

We use the distributive property (FOIL method) for the multiplication:

(4+j3)(5j3)=45+4(j3)+j35+j3(j3)(4 + j3)(5 - j3) = 4 \cdot 5 + 4 \cdot (-j3) + j3 \cdot 5 + j3 \cdot (-j3)

Now, calculate each term separately:

  1. 45=204 \cdot 5 = 20
  2. 4(j3)=j124 \cdot (-j3) = -j12
  3. j35=j15j3 \cdot 5 = j15
  4. j3(j3)=9j3 \cdot (-j3) = -9 (since j2=1j^2 = -1)

Combine these results:

20j12+j15920 - j12 + j15 - 9

Now, combine the real and imaginary parts:

  • Real part: 209=1120 - 9 = 11
  • Imaginary part: j12+j15=j3-j12 + j15 = j3

So, the voltage VV is:

V=11+j3V = 11 + j3

Thus, the voltage of the circuit is 11+j311 + j3 volts.

Do you want more details or have any questions?

Here are 5 questions you can ask next:

  1. How do I perform operations on complex numbers?
  2. Can you explain the concept of impedance in AC circuits?
  3. How do I convert a complex number from rectangular to polar form?
  4. What is the significance of the imaginary unit jj in electrical engineering?
  5. Can you solve another problem involving complex numbers in electrical circuits?

Tip: When working with complex numbers in electrical engineering, always remember to separate real and imaginary parts for easier calculation and interpretation.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Electrical Engineering

Formulas

Voltage formula: V = I * R

Theorems

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Suitable Grade Level

Advanced