The resistance, R, of a circuit containing these unknown components is (5x+20)Ω

. A 90-volt potential difference across the circuit produces a current of 2.25 amps.

What is the resistance of the unknown component?

1 answer

To find the resistance \( R \) of the unknown components, we can use Ohm's Law, which states:

\[ V = I \times R \]

where:

  • \( V \) is the voltage (90 volts),
  • \( I \) is the current (2.25 amps),
  • \( R \) is the resistance.

We need to find \( R \) in terms of the given expression \( 5x + 20 \).

First, we can rearrange Ohm's Law to solve for \( R \):

\[ R = \frac{V}{I} \]

Substituting the given values:

\[ R = \frac{90 , \text{volts}}{2.25 , \text{amps}} = 40 , \Omega \]

Now we equate this to the expression for the resistance given by the unknown components:

\[ 5x + 20 = 40 \]

Next, we solve for \( x \):

\[ 5x + 20 = 40 \] \[ 5x = 40 - 20 \] \[ 5x = 20 \] \[ x = \frac{20}{5} = 4 \]

Now that we have \( x = 4 \), we can substitute it back to find the resistance:

\[ R = 5x + 20 = 5(4) + 20 = 20 + 20 = 40 , \Omega \]

Thus, the resistance of the unknown component is:

\[ \boxed{40 , \Omega} \]