Electricity and Magnetism
# Resistors

AC-1: imperceptible

AC-2: pain, but no muscle contraction

AC-3: pain with muscle contraction

AC-4: possible irreversible effects

AC-4.1: up to 5% probability of ventricular fibrillation

AC-4.2: 5-50% probability of fibrillation

AC-4.3: over 50% probability of fibrillation

The table above shows the corresponding physiologic effects when a person is electrocuted by an alternating current according to the time duration of the shock and the magnitude of current that flows through his/her body. The resistance of a human body (when the skin is dry) when shocked by 110 Volts is known to be about 2,000 Ohms. What will happen when Bryan gets electrocuted for 0.5 seconds while plugging his Xbox into a 110-Volt outlet?

**Details and Assumptions**

- Ventricular fibrillation is a type of heart attack.

*electroplaques*. It is discovered that a typical eel contains $140$ rows of $5000$ electroplaques, where each electroplaque is capable of generating an EMF of $0.15$ volts. The internal resistance of an electroplaque is approximately $0.25\ \Omega$. If the water surrounding the eel has a resistance of $800\ \Omega$, how strong is the maximum current (in Amperes) produced by the electric eel in the water?

This is my favourite circuits problem from *Fundamentals of Physics* by Halliday, Resnick, Walker.

**Clarification:** There are $140$ rows with $5000$ electroplaques, and each row is connected **in parallel**.

$l$ has a uniform cross section.

A conductor of lengthThe radius of cross section varies linearly from $a$ to $b$.The resistivity of the material is $\rho$.

Find the resistance of the conductor across its ends **in Ohms**.

**Details and Assumptions**

- $\rho$=$6.28\times$$10^{-8}$$\Omega$m
- $l$ (length of conductor) =10 cm
- $a$=2 cm and $b$=5 cm