A company makes two electronic circuit boards that require the same resistance. The Pro-X board runs on 120 volts, while the Pro-I board runs on 90 volts. If the current running through the Pro-I board is 15 fewer milliamps (mA) than the current running through the Pro-X board, how much current is running through each board? Which of the following rational equations bests models this situation?

Respuesta :

Answer:

60 mA and 45 mA

[tex]\displaystyle \frac{120}{R}=\frac{90}{R}+0.015[/tex]

Step-by-step explanation:

Application of Linear Equations

The voltage V measured in a resistive element of an electrical circuit or resistance R is

[tex]V=I.R[/tex]

Where I is the current flowing through the resistor. Solving for I

[tex]\displaystyle I=\frac{V}{R}[/tex]

There are two electronic circuit boards that have the same resistance. The Pro-X board runs on 120 volts and the Pro-I board runs on 90 Volts. We know that the current running through this last one is 15 mA fewer than the current through the Pro-X board. It means

[tex]\displaystyle \frac{120}{R}=\frac{90}{R}+0.015[/tex]

Rearranging:

[tex]\displaystyle \frac{120}{R}-\frac{90}{R}=0.015[/tex]

Operating

[tex]\displaystyle \frac{30}{R}=0.015[/tex]

Or, equivalently

[tex]\displaystyle R=\frac{30}{0.015}=2000\Omega[/tex]

Thus, the current through the Pro-X board is

[tex]\displaystyle \frac{120}{2000}=60\ mA[/tex]

And the current through the Pro-I board is

[tex]\displaystyle \frac{90}{2000}=45\ mA[/tex]