Independent variable represents the external condition affecting the system. This is the variable that is changed by the researcher to observe how it affects the dependent variable. It is considered the cause or the input that is controlled to test its effects on the outcome. The independent variable is what you change or control in an experiment to explore its impact. A dependent variable, on the other hand, represents the physical quantity of the system, which is affected by the external condition. This variable is the outcome or the effect that is measured in the experiment. It depends on the independent variable, changing in response to alterations in the independent variable.
They are usually connected via function, e. g. linear dependency can be described as:
Dependent variable = constant * Independent variable.