In this topic, you study Ohm’s Law – Statement & Theory.
This is the basic law used in the field of electrical engineering. It gives the relationship between the potential difference (V), the current (I) and the resistance (R) Of a d.c. circuit. Dr. Ohm in 1827 discovered that the current flowing through a solid conductor is directly proportional to the difference Of potential across the conductor, provided the temperature remains constant. He also found that this current is inversely proportional to the resistance of the conductor.
Ohm’s Law Statement
Thus, combining these two experimental results, Ohm’slaw can be stated as follows:
The current flowing through a solid conductor is directly proportional to the difference of potential across the conductor and inversely proportional to its resistance, provided the temperature remains constant.
From the above relationship, the practical units for resistance, potential difference and current may be defined as follows:
Ohm: It is the resistance of a conductor which requires the application of one volt across its terminals in order that the current Of one ampere may flow through it. Volt: It is the potential difference across a resistance of one ohm carrying a current of one ampere. Ampere: It is that current which flows in a conductor having the resistance of one ohm when the potential difference of one volt is a lied across its terminals.
Example 2.1: An ammeter connected in series with an unknown resistance reads 0.5 A (Fig. 2.1). A voltmeter placed across the ends Of the resistance shows a reading Of 25 V. Compute the value of the resistance.