Voltage
Consider a portable battery charger for a phone needs to deliver 20 W of power for fast charging. If the current passing through is 4 amps, what is the battery’s output voltage (V)?
Expand Hint
Power absorbed by a resistive element:
$$$P=VI=\frac{V^{2}}{R}=I^2R$$$
where
$$V$$
is voltage,
$$I$$
is current, and
$$R$$
is resistance.
Hint 2
Based on the problem statement’s givens, solve for voltage using the equation:
$$$P=VI$$$
Power absorbed by a resistive element:
$$$P=VI=\frac{V^{2}}{R}=I^2R$$$
where
$$V$$
is voltage,
$$I$$
is current, and
$$R$$
is resistance.
Solving for Voltage using the problem statement’s knowns:
$$$P=VI\rightarrow 20W=V(4A)$$$
$$$V=\frac{20W}{4A}=5\:V$$$
5 V
Time Analysis
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