5···+ SerCP10 17P011. My Notes Ask Your Teacher -/2 points A person notices a mi

Question

5···+ SerCP10 17P011. My Notes Ask Your Teacher -/2 points A person notices a mild shock if the current along a path through the thumb and index finger exceeds 77 A. Compare the maximum possible voltage without shock across the thumb and index finger with a dry-skin resistance of 4.3 x 105 and a wet-skin resistance of 2,300 . dry skin wet skin 6. 2 points SerCP11 17.P020 My Notes Ask Your Teacher A rectangular block of copper has sides of length 16 cm, 22 cm, and 42 cm. If the block is connected to a 7.2 V source across two of its opposite faces, find the following. (a) What is the maximum current the block can carry? (b) What is the minimum current the block can carry? Need Help? ReadWatch

Explanation / Answer

5.

These questions are about the application of ohm's law, which can be stated as

voltage = current*resistance

V = I*R

Dry skin

V= 77*10-6*4.3*105

= 33.11V

Wet skin

V = 77*10-6*2300

= 177mV

6.

This question has to do with resistivity.

Resitance = resistivity * length / area.

Therefore, the longest and thinnest shape will have the greatest resistance, and the widest and short shape will carry the most current.
Resistivity of copper is 1.7*10-8
R min = resistivity * 16/ ( 22 * 42)

=2.94*10-8
R max = resistivity * 42 / (16 * 22)

=2.03*10-7
Make sure you change centimeters to whatever units the resistivity has.
Then using the ever popular V = I R
Imax = 7.2 / Rmin

=2.44*108amperes
Imin = 7.2 / Rmax

=3.54*107 ampers

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