Problem

Calculate the current through a single loop circuit if $\varepsilon = 120 \, \mathrm{V}$, $R = 1000 \, \Omega$, and $r = 0.01 \, \Omega$.

Data

• EMF: $\varepsilon = 120 \, \mathrm{V}$
• Resistance: $R = 1000 \, \Omega$
• Internal Resistance: $r = 0.01 \, \Omega$

Prerequisite Concept

• Current Formula:
  $I = \frac{\varepsilon}{R + r}$

Solution

Substitute the values:

$$I = \frac{120}{1000 + 0.01} = \frac{120}{1000.01} = 0.1199 \, \mathrm{A}.$$

Convert to milliamperes:

$$I = 119.9 \, \mathrm{mA}.$$

Answer

• Current: $I = 0.1199 \, \mathrm{A}$

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