Ohm's Law:

OHM’s law states that - Electric current flowing through an ideal conductor is directly proportional to the Potential Difference across its ends. It is named after the a German physicist Georg Simon Ohm In 1827.

Mathematically,

V ∝ I

V = I x R

where:

• V is the voltage (measured in volts),
• I is the current (measured in amperes), and
• R is the resistance (measured in ohms). It is a constant of proportionality.

Resistance is a property of conductor to resist flow of charge through it. Its SI unit is Ohm (Ω).

Note: Ohm’s Law holds true only when temperature remains the same.

1. Calculate the resistance if 5 A of electric current flows through a conductor having potential difference between two points is equal to 15 V.
   Given:
   Current (I) = 5 A, Voltage (V) = 15 V
   To find Resistance (R)
   We know,
   V = I x R
   R = V/I = 15 / 5 = 3 Ω
2. If the resistance of an electric iron is 48 Ω and an electric current of 5 A is flowing through it, what will be the potential difference between two terminals of electric iron.
   Given:
   Resistance (R) = 48 Ω, I = 5 A
   To find Voltage (V)
   We know,
   V = I x R = 5 x 48 = 240 V

3. The values of current I flowing in a given resistor for the corresponding values of potential difference V across the resistor are given below –

   I (amperes) 0.5 1.0 2.0 3.0   4.0

   V (volts)      1.6 3.4 6.7 10.2 13.2

   Plot a graph between V and I and calculate the resistance of that resistor.

   Solution:    We know, Ohm’s Law – V = I x R or R = V/I

   I (amperes)	V (volts)	R (ohms), From ohm’s Law R = V / I
   0.5	1.6	1.6/0.5    = 3.2
   1.0	3.4	3.4/1.0    = 3.4
   2.0	6.7	6.7/2.0    = 3.35
   3.0	10.2	10.2/3.0  = 3.4
   4.0	13.2	13.2/4.0  = 3.3

    

        

        

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