BIO Effect of
A potential difference across two parts of the body (for example, the 120-V potential difference from a wall socket from one hand to the other or from the hands to the feet) can initiate an electric current in the body that stimulates nerve endings and triggers nerve signals that cause muscular contraction. Even worse, the current in the body can upset the rhythmic electrical operation of the heart. The heart muscles might be stimulated randomly in what is called ventricular fibrillation—a random contraction of the ventricles, which can be deadly. A rough guide to the effects of electric current on the body at different current levels is provided in Figure 19.39. Under dry conditions, human skin has high electrical resistance. Wet skin dramatically lowers the body’s resistance and makes electrocution more likely to occur.
The electrical resistance across wet skin is about 1000 Ω. Suppose a person with wet skin puts one hand on a 120-V power cord from a home wall socket while the other hand is touching a metal object at 0 V (at what is called ground). Which condition described below is most likely to occur?
a. No sensation
b. Threshold of pain
c. Cannot let go
d. Ventricular fibrillation
e. Severe burns and shock
Want to see the full answer?
Check out a sample textbook solutionChapter 19 Solutions
College Physics
Additional Science Textbook Solutions
Tutorials in Introductory Physics
Life in the Universe (4th Edition)
University Physics with Modern Physics (14th Edition)
College Physics: A Strategic Approach (4th Edition)
The Cosmic Perspective (8th Edition)
Conceptual Integrated Science
- In places such as hospital operating rooms or factories for electronic circuit boards, electric sparks must be avoided. A prison standing on a grounded floor and touching nothing else can typically have a body capacitance of 150 pF, in parallel with a foot capacitance of 80.0 pF produced by the dielectric soles of his or her shoes. The person acquires static electric charge from interactions with Ills or her surroundings. The static charge flows to ground through the equivalent resistance of the two shoe soles in parallel with each other. A pair of rubber-soled street shoes can present an equivalent resistance of 5.00 103 M. A pair of shoes with special static-dissipative soles can have an equivalent resistance of 1.00 M. Consider the persons body and shoes as forming an RC circuit with the ground. (a) How long does it take the rubber-soled shoes to reduce a persons potential from 3.00 103 V to 100? (b) How long does it take the static-dissipative shoes to do the same thing?arrow_forwardConstrue! Your Own Problem Consider a rechargeable lithium cell that is to be used to power a camcorder. Construct a problem in which you calculate the internal resistance of the cell during normal operation. Also, calculate the minimum voltage output of a battery charger to be used to recharge your lithium cell. Among the things to be considered are the emf and useful terminal voltage of a lithium cell and the current it should be able to supply to a camcorder.arrow_forwardSI. A physics student has a single-occupancy dorm loom. The student lias a small refrigerator that runs with a current of 3.00 A and a voltage of 110 V, a lamp that contains a 100-YV bulb, an overhead light with a 60-W bulb, and various other small devices adding up to 3.00 W. (a) Assuming the power plant that supplies 110 V electricity to the dorm is 10 km away and the two aluminum transmission cables use 0-gauge wire with a diameter of 8.252 mm, estimate the percentage of the total power supplied by the power company that is lost in the transmission, (b) What would be the result is the power company delivered the electric power at 110 kV?arrow_forward
- A heart defibrillator being used on a patient has an RC time constant of 10.0 ms due to the resistance of the patient and the capacitance of the defibrillator. (a) If the defibrillator has an 8.00F capacitance, what is the resistance of the path through the patient? (You may neglect the capacitance of the patient and the resistance of the defibrillator.) (b) If the initial voltage is 12.0 kV, how long does it take to decline to 6.00x102 V?arrow_forwardA man wishes to vacuum his car with a canister vacuum cleaner marked 535 W at 120. V. The car is parked far from the building, so he uses an extension cord 15.0 m long to plug the cleaner into a 120.-V source. Assume the cleaner has constant resistance. (a) If the resistance of each of the two conductors of the extension cord is 0.900 , what is the actual power delivered to the cleaner? (b) If, instead, the power is to be at least 525 W, what must be the diameter of each of two identical copper conductors in the cord the young man buys? (c) Repeat part (b) if the power is to be at least 532 W. Suggestion: A symbolic solution can simplify the calculations.arrow_forwardConstruct Your Own Problem Consider a person working in an environment where electric currents might pass through her body. Construct a problem in which you calculate the resistance of insulation needed to protect the person from harm. Among the things to be considered are the voltage to which the person might be exposed, likely body resistance (dry, wet, ...), and acceptable currents (safe but sensed, safe and unfelt, ...).arrow_forward
- Integrated Concepts A battery-operated car utilizes a 12.0 V system. Find the charge the batteries must be able to move in order to accelerate the 750 kg car from rest to 25.0 m/s. make it climb a 2.00 102 m high hill, and then cause it to travel at a constant 25.0 m/s by exerting a 5.00 102 N force for an hour.arrow_forwardYou have a faculty position at a community college and are teaching a class in automotive technology. You are deep in a discussion of using jumper cables to start a car with a dead battery from a car with a fresh battery. You have drawn the circuit diagram in Figure P27.16 to explain the process. The battery on the left is the live battery in the correctly functioning car, with emf and internal resistance RL, where the L subscript refers to live. Its terminals are connected directly across those of the dead battery, in the middle of the diagram, with emf and internal resistance RD, where the D subscript refers to dead. Then, the starter in the car with the dead battery is activated by closing the ignition switch, allowing the car to start. The resistance of the starter is RS. A student raises his hand and asks, So is the dead battery being charged while the starter is operating? How do you respond? Figure P27.16arrow_forwardAn electronic apparatus may have large capacitors at high voltage in the power supply section, presenting a shock hazard even when the apparatus is switched off. A “bleeder resistor" is therefore placed across such a capacitor, as shown schematically in Figure 21.50, to bleed the charge from it after the apparatus is off. Why must the bleeder resistance be much greater than the effective resistance of the rest of the circuit? How does this affect the time constant for discharging the capacitor?arrow_forward
- Integrated Concepts Use the ECG in Figure 20.34 to determine the heart rate in beats per minute assuming a constant time between beats. Figure 20.34 A lead II ECG with corresponding arterial blood pressure. The QRS complex is created by the depolarization and contraction of the ventricles and is followed shortly by the maximum or systolic blood pressure. See text for further description.arrow_forwardIntegrated Concepts A flashing lamp in a Christmas earring is based on an RC discharge of a capacitor through its resistance. The effective duration of the flash is 0.250 s, during which it produces in average 0.500 W from an average 3.00 V. (a) What energy does it dissipate? (b) How much charge moves through the lamp? (c) Find the capacitance. (d) What is the resistance of the lamp?arrow_forwardIntegrated Concepts (a) An immersion heater utilizing 120 V can raise the temperature of a 1.00 102 -g aluminum cup containing 350 g of water from 20.0°C to 95.0°C in 2.00 min. Find its resistance, assuming it is constant during the process. (b) A lower resistance would shorten the heating time. Discuss the practical limits to speeding the heating by lowering the resistance.arrow_forward
- College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- Physics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning