DC CIRCUITS ELECTRIC CURRENT Electric current is

DC CIRCUITS

ELECTRIC CURRENT Electric current is traditionally defined as the ordered flow of electrons in a conductor.

There are two types of electric current The first type is called direct current (DC), the second type is called alternating current (AC).

DC Direct current is the current which always flows in one direction. One directions is from positive potential (+) to negative potential (-), and it is called technical direction of DC flow. The second direction is from negative potential (-) to positive potential (+), and it is called scientific direction of DC.

RESISTORS IN SERIES A simple SERIES CIRCUIT is shown in the diagram below. The current (I) at every point in a series circuit equals the current leaving the battery. I 1= I 2=I 3=ITotal

RESISTORS IN SERIES Assuming that the connecting wires offer no resistance to current flow, the potential difference between the terminals of the battery (V) equals the sum of the potential differences across the resistors. V=V 1+ V 2+ V 3 The equivalent electrical resistance (R) for this combination is equal to the sum of the individual resistors. R=R 1+ R 2+ R 3

RESISTORS IN PARALLEL In a simple PARALLEL CIRCUIT, the current leaving the battery divides at junction point A in the diagram shown below and recombines at point B. The battery current (I) equals the sum of the currents in the branches. In general I = I 1 + I 2 + I 3

RESISTORS IN PARALLEL If no other resistance is present, the potential difference across each resistor equals the potential difference across the terminals of the battery. The equivalent resistance (R) of a parallel combination is always less than the smallest of the individual resistors. The formula for the equivalent resistance is as follows: 1/R = 1/R 1 + 1/R 2 + 1/R 3 The potential difference across each resistor in the arrangement is the same. V = V 1 = V 2 = V 3