/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 29 A fisherman has netted a torpedo... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 26: Problem 29

A fisherman has netted a torpedo ray. As he picks it up, this electric fish creates a short-duration \(50 \mathrm{V}\) potential difference between his hands. His hands are wet with salt water, and so his skin resistance is a very low \(100 \Omega .\) What current passes through his body? Will he feel this DC pulse?

Short Answer

Expert verified
The current that passes through the fisherman's body is 500mA. Yes, the fisherman will feel the DC pulse as the current value is much higher than the typical sensory threshold for humans.

Step by step solution

01

Identify the given parameters

Given that the potential difference (V) is 50V, and the resistance (R) is 100 Ohms.
02

Apply Ohm's law

The formula for Ohm's law is \(I = \frac{V}{R}\). Substitute the given values into the equation: \(I = \frac{50V}{100 \Omega}\).
03

Calculate the current

Calculating the values in the equation will give the current (I): \(I = 0.5A = 500mA\). This is the current that passes through the fisherman's body.
04

Determine if the fisherman will feel the DC pulse

The sensory threshold for feeling an electrical shock typically is over 5mA. As the calculated current is 500mA, which is higher than 5mA, hence, the fisherman will feel the DC pulse.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Electric Current
Electric current can be compared to the flow of water through a pipe, representing the movement of electric charges (typically electrons) through a conductor. The unit of electric current is the ampere (A), and it is measured by how many charges pass through a given point in a second. In simpler terms, the greater the number of electrons flowing, the higher the current.

In the provided exercise, the wet hands of the fisherman conduct electricity allowing a current to flow through his body when the electric fish generates a potential difference. The value of the electric current, calculated by Ohm's Law as 0.5A or 500mA (milliamperes), indicates a substantial flow of electric charges between his hands.
Electrical Resistance
Electrical resistance is an obstruction to the flow of electric current, similar to friction in mechanical systems. It is measured in ohms (\( \text{惟} \) ). Factors affecting resistance include the material's properties, temperature, length, and cross-sectional area. Materials with low resistance, such as metals, are good conductors, while those with high resistance are insulators, like rubber.

The exercise shows that the fisherman's wet, salty hands have a low skin resistance of just 100 ohms. This reduced resistance is due to the presence of salt which contains ions, enhancing the conductivity of water. This explains why wet skin is more prone to electric shock than dry skin, as the resistance is significantly decreased, thereby allowing more current to flow.
Potential Difference
Potential difference, often referred to as voltage, is a measure of the work done to move a charge between two points in an electric field. The unit for potential difference is the volt (V). It is called a 'difference' because it represents the variance in electric potential energy between two locations.

Within the context of the problem, the torpedo ray creates a 50V potential difference which propels electrons to move through the fisherman's body, thereby generating an electric current. The presence of a potential difference is what causes the electric current to flow; without it, there would be no 'push' to move the electrons. In everyday life, battery terminals have a potential difference between them that causes current to flow when connected in a circuit.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The manufacturer of an electric table saw claims that it has a 3.0 horsepower motor. 1 horsepower is approximately 750 W. It is designed to be used on a normal \(120 \mathrm{V}\) outlet with a \(15 \mathrm{A}\) circuit breaker. Is this claim reasonable? Explain.

In an old house, the wires leading to a \(120 \mathrm{V}\) outlet have a total resistance of \(0.45 \Omega .\) When you plug in a hair dryer, it draws a 12 A current. a. How much does the outlet voltage decrease due to the voltage drop across the wires? b. What is the power dissipated as heat in the wires?

The girl in Figure 26.12 of the chapter has her hand on the sphere of a Van de Graaff generator that is at a potential of \(400,000 \mathrm{V}\). She is standing on an insulating platform, so no current flows through her. But what happens if she touches something that is grounded? Is she still safe? Figure \(P 26.57\) shows the equivalent circuit. \(C_{\mathrm{VDG}}=20 \mathrm{pF}\) represents the capacitance of the Van de Graaff sphere, \(C_{\text {girl }}=100 \mathrm{pF}\) is the capacitance of the girl's body, and \(R=5 \mathrm{k} \Omega\) is the resistance of her body, from one hand to the other. The switch is closed when she touches ground. What is the initial current at the instant the switch is closed? b. What is the time constant for the current to decay? c. Occupational safety experts have found that a shock is safe if the product of the voltage, the current, and the time the current is delivered is less than \(13.5 \mathrm{V} \cdot \mathrm{A} \cdot \mathrm{s}=13.5 \mathrm{J}\) (see Problem 26.28). Estimate this product. Is this shock safe?

Occupational safety experts have developed an alternative criterion for electrical safety. They have found that shocks lasting less than 3 s will be nonlethal if the product of the voltage drop across the body, the current through the body, and the time \((\leq 3.0 \mathrm{s})\) that the current flows does not exceed \(13.5 \mathrm{V} \cdot \mathrm{A} \cdot \mathrm{s}=13.5 \mathrm{J} .\) Suppose that one hand of a potential victim is grounded and the other hand touches a voltage source; suppose further that his skin resistance is negligible \(-\) a worstcase scenario. Using the criterion above, what is the lowest voltage that will not be lethal for a shock that lasts \(1.0 \mathrm{s} ?\)

Electricity is distributed to neighborhoods at a relatively high AC voltage, often \(7200 \mathrm{V}\). Transformers mounted on utility poles then transform this high voltage down to the \(120 \mathrm{V}\) used in homes. A typical transformer of this kind can handle as much as \(15 \mathrm{kW}\) of electric power flowing through it from its primary to its secondary. What is the primary current at this maximum power?
See all solutions

Recommended explanations on Physics Textbooks

Famous Physicists

Read Explanation

Dynamics

Read Explanation

Physical Quantities And Units

Read Explanation

Measurements

Read Explanation

Solid State Physics

Read Explanation

Classical Mechanics

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.