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Resistance and Ohm’s Law. Resistance and Ohm’s Law. The ability of materials to oppose the flow of electric charges is known as resistance . The circuit component that models this property is a resistor , as shown below. The value of the resistor is R. The Unit of R is Ohms ( Ω).
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Resistance and Ohm’s Law ECE 201
Resistance and Ohm’s Law • The ability of materials to oppose the flow of electric charges is known as resistance. The circuit component that models this property is a resistor, as shown below. The value of the resistor is R. • The Unit of R is Ohms (Ω). ECE 201
Ohm’s Law • Georg Simon Ohm experimentally observed that there is a direct relationship between the current flowing through a material and the voltage difference across it’s terminals. • This is expressed as Ohm’s Law, the most common form of which is v = iR. ECE 201
Reference choices for v, i ECE 201
Alternate forms of Ohm’s Law ECE 201
Conductance, G • Conductance is the reciprocal of resistance • Symbol is G • Unit is S (siemens) • Alternate unit is mho (ohm spelled backwards) • Used to simplify calculations ECE 201
Power in a resistor ECE 201