Question

A circuit has two resistances in series: 42 ohm and 14 ohm. If the current in the current is 0.5 amperes, what's the voltage drop across the 42 ohm resistor?

Answer 1

Explanations & Calculations

• Voltage drop ($\small V$) across a resistor during a current flow ($\small i$ ) through it is given by $\small V=iR$.
• In a circuit in which the components are in series, the same current flows through each component.
• In view of these facts,

Voltage drop across 42 Ohm resistor,

$\qquad\qquad \begin{aligned} \small V_{42} &= \small 0.5A \times 42\Omega\\ &= \small \bold{21V} \end{aligned}$

Voltage across 14 Ohm resistor,

$\qquad \begin{aligned} \small V &= \small 0.5A \times 14 \Omega\\ &= \small \bold{7V} \end{aligned}$