10 2 20 V Si Figure P1.77

A variable resistor enables one to change the resistance.  One design involves a horizontal tube of wire with a slider on the top.  By moving the slider, one can change the length of wire involved, thus changing the resistance.  Imagine a tube of wire with one layer made from wire 1.00 mm in diameter wrapped in a single layer with no gaps between the loops of wire ( the wire looks like a solid layer down the length of the tube).  The radius of the tube is 2.50 cm.  Moving the slider 1.00 cm changes the resistance of the variable resistor by 3.00 Ohms.  What is the resistivity of the wire, and what is it made of?

can someone show me how to do this problem and explain the answer step by step

(a) defibrillator sends a 6 A current through the chest of a patient by applying a 11000 V potential as in the figure. What is the resistance of the path (through the wire and the body)? -aira R= (b) The defibrillator paddles make contact with the patient through a conducting gel that greatly reduces the path resistance. To understand the importance of using the gel, discuss the difficulties that would ensue if a larger voltage were used to produce the same current through the patient, but with the path having perhaps 50 times the resistance by finding the ratio, P no-gel P gel e- ΚΩ (Hint: The current must be about the same, so a higher voltage would imply greater power. Use this equation for power: P = PR.) What difficulties arise when no gel is used? a. The voltage is too high for the human body even when the current is the same. b. There is a risk of skin burns because of the high power deposited.