A conductor of a radius r, length l and resistivity ρ has resistance R. It us melted down and formed into a new conductor, also cylindrical, with one fourth the length of the original conductor. The resistance of the new conductor is: a. R/16
b. R/4
c. R
d. 4R
e. 16R

Asimply means that over time there was some sort of change.

Laboratory experiments, observational field studies, and model-building are all examples of different forms of scientific investigations.  in what way do laboratory experiments primarily differ from other forms of scientific investigations?   a.  a laboratory experiment is the only accepted form of investigation within the scientific community.  b.  studies about how things behave in nature or studies involving very large objects are best answered through laboratory experiments.  c.  laboratory experiments involve the identification and control of variables.  d.  data can only be generated through laboratory experiments, not other forms of investigation.

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.