Short Answer 
Ohm’s Law defines the relationship between voltage, current, and resistance, asserting that current is proportional to voltage under constant resistance. However, this principle, represented by V=IR, has limitations, particularly for non-ohmic materials and in cases where factors like temperature and frequency alter resistance, leading to non-linear relationships in components like semiconductors.
Step 1: Understanding Ohm’s Law
Ohm’s law establishes a relationship between voltage (V), current (I), and resistance (R). The law asserts that the current flowing through a conductor is directly proportional to the voltage across it, assuming the temperature remains constant. However, this relationship is based on the condition that the resistance is constant and linear, which may not be true for all materials.
Step 2: Limitations of V=IR
The equation V=IR represents Ohm’s law but oversimplifies the relationship for non-ohmic materials. In many cases, factors such as temperature, frequency, or inherent material properties can alter resistance. This means that doubling the voltage may not lead to a simple doubling of the current, challenging the assumption of constant resistance.
Step 3: Recognizing Non-Linear Relationships
In certain components like semiconductors, or in complex circuits, the relationship between voltage and current can be non-linear. It’s important to consider other factors such as capacitance and inductance which can affect circuit behavior. Thus, while V=IR is a helpful guideline, it is not universally applicable across all electrical scenarios.