AP Physics Help--Emergency My physics teacher sometimes gives out rediculously difficult worksheets. I'm having trouble with one problem in particular: A breathing monitor girds a patient with a mercury-filled rubber tube and measures the variation on tube resistance. The tube has an unstretched length of 1.25 m and inside diameter of 2.51 mm. The monitor is connected to a 100-mV power supply, and the total resistance of the circuit is that due to the mercury plus 1.00 Ω (an internal resistance of the power supply). Determine the change of current through the monitor as the patient draws a breath and stretches the hose by 10.0 cm. Take ρ(Hg) = 9.40 x 10^(-7) Ω ◦ m. Any help would be greatly appreciated.