ELECTRIC CURRENT. PHYSIOLOGICAL EFFECT OF CURRENT 1. The electric field E is defined to be E =5 where F is the electrostatic force exerted on a small positive test charge q . E has units of N/C. 2. In uniform electric field the potential difference is AV = Ed, where E is electric field and d'is the distance from A to B, or the distance between the plates. 3. A capacitor is a device used to store charge. The amount of charge q a capacitor can store depends on two major factors - the voltage applied and the capacitor's physical characteristics, such as its size. The capacitance C is the amount of charge stored per volt, or C = , units Farad (F). 4. Capacitance of a parallel plate capacitor C = f, where e, = 8.85 - 10-12 F/m is called the permittivity of free space, e is the dielectric constant of the material, A is area of plates and d is distance between plates. 5. Capacitors are used in a variety of devices, including defibrillators, microelectronics such as calculators, and flash lamps, to supply energy. The energy stored in a capacitor can be expressed in three where q is the charge (C), AV'is the voltage (V), and Cis the capacitance of the ways: E = capacitor(F). 6. Electric current I is the rate at which charge flows, given by / =, units Amperes (A). Here q is the amount of charge passing through an area in time t . 7. Current density is current per unit of cross sectional area / = units A/m'. 8. Ohm's law. One statement of Ohm's law gives the relationship between current I, voltage V , and resistance R in a simple circuit to be I = . Here R is resistance in units of ohms ( 2). 9. Electric power. p=AV ·1 = 1°R = 10. Heat effect of electrical current Q =AV 1·t = 1°R¢ = 11. Resistors connections (a) in series R = Rị + R2 + R3 ..+ RN (b) in parallel = + 20" Av2 R. R, (a) R1 here N total is number of the resistors. R2 R3 RN R, Table 1 - Effects of Electrical Shock as a Function of Current Current Effect Current (mA) 50 Effect (mA) | 1 Onset of pain Ventricular fibrillation possible; often fatal. Threshold of sensation Maximum harmless current 100-300 depending 300 Onset of burns concentration of current on Onset of sustained muscular contraction; cannot let go for duration of shock; contraction of chest muscles may stop breathing | during shock Onset of sustained ventricular contraction and respiratory paralysis; both cease when shock ends; heartbeat may return to normal; used to defibrillate the heart 10-20 6000 ww Table 2 Drd not shockedi Cu ow Resistance, Current path Current, A Person (SHOCKEDN Ohms 1300 1000 650 Hgh Vage Hand-body-hand One hand-body-feet Ac S and Load Hands-body-feet Foot-foot 1300
ELECTRIC CURRENT. PHYSIOLOGICAL EFFECT OF CURRENT 1. The electric field E is defined to be E =5 where F is the electrostatic force exerted on a small positive test charge q . E has units of N/C. 2. In uniform electric field the potential difference is AV = Ed, where E is electric field and d'is the distance from A to B, or the distance between the plates. 3. A capacitor is a device used to store charge. The amount of charge q a capacitor can store depends on two major factors - the voltage applied and the capacitor's physical characteristics, such as its size. The capacitance C is the amount of charge stored per volt, or C = , units Farad (F). 4. Capacitance of a parallel plate capacitor C = f, where e, = 8.85 - 10-12 F/m is called the permittivity of free space, e is the dielectric constant of the material, A is area of plates and d is distance between plates. 5. Capacitors are used in a variety of devices, including defibrillators, microelectronics such as calculators, and flash lamps, to supply energy. The energy stored in a capacitor can be expressed in three where q is the charge (C), AV'is the voltage (V), and Cis the capacitance of the ways: E = capacitor(F). 6. Electric current I is the rate at which charge flows, given by / =, units Amperes (A). Here q is the amount of charge passing through an area in time t . 7. Current density is current per unit of cross sectional area / = units A/m'. 8. Ohm's law. One statement of Ohm's law gives the relationship between current I, voltage V , and resistance R in a simple circuit to be I = . Here R is resistance in units of ohms ( 2). 9. Electric power. p=AV ·1 = 1°R = 10. Heat effect of electrical current Q =AV 1·t = 1°R¢ = 11. Resistors connections (a) in series R = Rị + R2 + R3 ..+ RN (b) in parallel = + 20" Av2 R. R, (a) R1 here N total is number of the resistors. R2 R3 RN R, Table 1 - Effects of Electrical Shock as a Function of Current Current Effect Current (mA) 50 Effect (mA) | 1 Onset of pain Ventricular fibrillation possible; often fatal. Threshold of sensation Maximum harmless current 100-300 depending 300 Onset of burns concentration of current on Onset of sustained muscular contraction; cannot let go for duration of shock; contraction of chest muscles may stop breathing | during shock Onset of sustained ventricular contraction and respiratory paralysis; both cease when shock ends; heartbeat may return to normal; used to defibrillate the heart 10-20 6000 ww Table 2 Drd not shockedi Cu ow Resistance, Current path Current, A Person (SHOCKEDN Ohms 1300 1000 650 Hgh Vage Hand-body-hand One hand-body-feet Ac S and Load Hands-body-feet Foot-foot 1300
University Physics Volume 1
18th Edition
ISBN:9781938168277
Author:William Moebs, Samuel J. Ling, Jeff Sanny
Publisher:William Moebs, Samuel J. Ling, Jeff Sanny
Chapter1: Units And Measurement
Section: Chapter Questions
Problem 15P: Use the orders of magnitude you found in the previous problem to answer the following questions to...
Related questions
Question
Lower voltage and higher frequency are considered less dangerous for human health and life. In the United States of America the standard voltage is 120 V and the frequency is 60 Hz (European standard voltage is 220 V). (a) Calculate the value of a current flowing through a person, for different current paths (Table 2). (b) What was the power dissipated in his body? (c) Using Table 1 make conclusion about physiological effect of these currents.
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
Step by step
Solved in 3 steps with 2 images
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.Recommended textbooks for you
University Physics Volume 1
Physics
ISBN:
9781938168277
Author:
William Moebs, Samuel J. Ling, Jeff Sanny
Publisher:
OpenStax - Rice University
Glencoe Physics: Principles and Problems, Student…
Physics
ISBN:
9780078807213
Author:
Paul W. Zitzewitz
Publisher:
Glencoe/McGraw-Hill
University Physics Volume 1
Physics
ISBN:
9781938168277
Author:
William Moebs, Samuel J. Ling, Jeff Sanny
Publisher:
OpenStax - Rice University
Glencoe Physics: Principles and Problems, Student…
Physics
ISBN:
9780078807213
Author:
Paul W. Zitzewitz
Publisher:
Glencoe/McGraw-Hill