As few as possible.
In any experiment there are many kinds of variables that will effect the experiment. The independent variable is the manipulation for the experiment and the dependent variable is the measure you take from that experiment. Confounding variables are things in which have an effect on the dependent variable, but were taken into account in the experimental design. For example, you want to know if Drug X has an effect on causing sleep. The experimenter must take care to design the experiment so that he can be very sure that the subjects in the study fell asleep because of the influence of his Drug X, and that the sleepiness was not caused by other factors. Those other factors would be confounding variables.
in a science experiment many things are measured. it depends on what experiment one is conducting.
five
Infinitely many. Assuming the variables are "x" and "y" , for every value of "x" a value for "y" can be calculated.
One
In a properly designed experiment, it is important to have at least 2 controlled variables. With two variables you are able to remove one at a time and see the effect in your setup.
An experiment of any kind can have infinitely many variables. A controlled experiment can have just as many, provided that all but one are kept exactly the same.
All variables except one, the experimental variable, are kept constant in an experiment.
5
one
As few as possible.
1
There are three types of variables tested: manipulated variables, controlled variables, and experimental variables.
There are complex models that allow researchers to study several variables if the experiment is carefully designed and very carefully carried out. These models can show whether a variety of variable interactions occur, and if that is your focus then these models are good. But the best experiments investigate a small number of variables, as few as one.
A experiment should only have one variable.
Most science experiments will have two independent variables. Fundamentally, an experiment will want as few variables as possible for better results.