Learning Materials
Features
Discover
Chapter 20: Q29CQ (page 732)
In view of the small currents that cause shock hazards and the larger currents that circuit breakers and fuses interrupt, how do they play a role in preventing shock hazards?
Since humans have the lowest resistance, a large current flows, and the fuse breaks the circuit.
Over 30 million students worldwide already upgrade their learning with Vaia!
All the tools & learning materials you need for study success - in one app.
Get started for free
In which of the three semiconducting materials listed in Table 20.1 do impurities supply free charges?
(Hint: Examine the range of resistivity for each and determine whether the pure semiconductor has the higher or lower conductivity.)
(a) What is the resistance of a \(20 - VAC\) short circuit that generates a peak power of \(96.8\;kW\)? (b) What would the average power be if the voltage was \(120{\rm{ }}V{\rm{ }}AC\)?
Two different electrical devices have the same power consumption, but one is meant to be operated on \(120 - V\) AC and the other on \(240 - V\)AC.
(a) What is the ratio of their resistances?
(b) What is the ratio of their currents?
(c) Assuming its resistance is unaffected, by what factor will the power increase if a \(120 - V\) AC device is connected to \(240 - V\) AC?
An electrified needle is used to burn off warts, with the circuit being completed by having the patient sit on a large butt plate. Why is this plate large?
(a) A defibrillator sends a \({\bf{6}}{\bf{.00}}\;{\bf{A}}\) current through the chest of a patient by applying a \({\bf{10000}}\;{\bf{V}}\) potential as in the figure below. What is the resistance of the path? (b) The defibrillator paddles make contact with the patient through a conducting gel that greatly reduces the path resistance. Discuss the difficulties that would ensue if a larger voltage were used to produce the same current through the patient, but with the path having perhaps 50 times the resistance. (Hint: The current must be about the same, so a higher voltage would imply greater power. Use the equation for power: \({\bf{P = }}{{\bf{I}}^{\bf{2}}}{\bf{R}}\).)
What do you think about this solution?
We value your feedback to improve our textbook solutions.
Explanations 
Textbooks 
Exams 
GCSE 
IGCSE 
AS 
A Level 
International A Level 
University Admissions Tests 
Flashcards 
Vaia AI 
Notes 
Study Plans 
Study Sets 
Find a job 
Find a degree 
Student Deals 
Magazine 
Mobile App