Ohm’s law states that at constant temperature, the current between two points of a conductor is directly proportional to the voltage (potential difference) across the two points.
I α V
Introducing the constant of proportionality, the resistance (R) we arrive at the mathematical equation that describes Ohm’s Law relationship as:
I = the current through the conductor in units of amperes (A)
V = the voltage measured across the two points of the conductor in units of volts (V), and
R = the resistance of the conductor in units of ohms (Ω).
From the mathematical relationship above, Ohm’s law can be restated thus:
At constant temperature, the current flowing through any two point of a conductor is directly proportion to its potential different (voltage applied) and inversely proportion to its resistance.
Ohm’s law parameters
Solved Examples on Ohm’s Law
Determine the current flowing through a conductor if voltage of 24V is placed across a 400ohm resistor.
SolutionVoltage (V) = 24V
Resistance (R) = 400 Ω
I = = 0.06A = 60mA
Find the potential difference across two points of a conductor if the a current of 10mA flows through a resistance 700Ω
V = IR = 0.01 x 700 = 7V.
From the circuit below, calculate the current (I), Conductance (G) and power dissipated (P)
Power dissipated (P) = VI = I2 R = (0.006)2 x 6000 = 216mW
Calculate the current through the resistor and the power dissipated if a voltage of 16Sinθ t is connected across a load of resistance 2kΩ.
Power dissipated (P) = VI = 16Sinθt x 8Sinθt = 128Sin2(θt) mW
At a voltage of 5Cosθ V, a resistor absorbs an instantaneous power of 25Cos2θ mW. Calculate:
- The value of the current (I) flowing through the circuit.
- The value of the resistor (R)