Consider the diagram shown below.
A voltmeter of resistance $ 150 \,\Omega $ . is connected across $A$ and $B$. The potential drop across and $C$ measured by voltmeter is
When voltmeter is connected across $A$ and $B$, the equivalent resistance of the circuit is
$R_{e q} =100+\frac{150 \times 100}{100+150}$$=100+\frac{15000}{250} $$=100+60=160\, \Omega$$\therefore$ Current, $i =\frac{50}{160}=\frac{5}{16} A$ .
Therefore, potential drop across $B$ and $C$ is
$V_{B C} =i R_{B C}$$=\frac{5}{16} \times 100$$=\frac{500}{16}=31.25 \,V$
The current electricity whose direction remains the same is known as direct current. Direct current is defined by the constant flow of electrons from a region of high electron density to a region of low electron density. DC is used in many household appliances and applications that involve a battery.
Alternating Current
The current electricity that is bidirectional and keeps changing the direction of the charge flow is known as alternating current. The bi-directionality is caused by a sinusoidally varying current and voltage that reverses directions, creating a periodic back-and-forth motion for the current. The electrical outlets at our homes and industries are supplied with alternating current.
