As in Example 27.2, consider a power supply with fixed emf ε and internal resistance r causing current in a load resistance R . In this problem, R is fixed and r is a variable. The efficiency is defined as the energy delivered to the load divided by the energy delivered by the emf. (a) When the internal resistance is adjusted for maximum power transfer, what is the efficiency? (b) What should be the internal resistance for maximum possible efficiency? (c) When the electric company sells energy to a customer, does it have a goal of high efficiency or of maximum power transfer? Explain. (d) When a student connects a loudspeaker to an amplifier, does she most want high efficiency or high power transfer? Explain.
As in Example 27.2, consider a power supply with fixed emf ε and internal resistance r causing current in a load resistance R . In this problem, R is fixed and r is a variable. The efficiency is defined as the energy delivered to the load divided by the energy delivered by the emf. (a) When the internal resistance is adjusted for maximum power transfer, what is the efficiency? (b) What should be the internal resistance for maximum possible efficiency? (c) When the electric company sells energy to a customer, does it have a goal of high efficiency or of maximum power transfer? Explain. (d) When a student connects a loudspeaker to an amplifier, does she most want high efficiency or high power transfer? Explain.
Solution Summary: The author explains the formula to calculate the efficiency when the internal resistance is adjusted for maximum power transfer.
As in Example 27.2, consider a power supply with fixed emf ε and internal resistance r causing current in a load resistance R. In this problem, R is fixed and r is a variable. The efficiency is defined as the energy delivered to the load divided by the energy delivered by the emf. (a) When the internal resistance is adjusted for maximum power transfer, what is the efficiency? (b) What should be the internal resistance for maximum possible efficiency? (c) When the electric company sells energy to a customer, does it have a goal of high efficiency or of maximum power transfer? Explain. (d) When a student connects a loudspeaker to an amplifier, does she most want high efficiency or high power transfer? Explain.
Two complex values are z1=8 + 8i, z2=15 + 7 i. z1∗ and z2∗ are the complex conjugate values.
Any complex value can be expessed in the form of a+bi=reiθ. Find θ for (z1-z∗2)/z1+z2∗. Find r and θ for (z1−z2∗)z1z2∗ Please show all steps
Calculate the center of mass of the hollow cone
shown below. Clearly specify the origin and the
coordinate system you are using.
Z
r
Y
h
X
12. If all three collisions in the figure below are
totally inelastic, which will cause more damage?
(think about which collision has a larger amount of
kinetic energy dissipated/lost to the environment?
I
m
II
III
A. I
B. II
C. III
m
m
v
brick wall
ע
ע
0.5v
2v
0.5m
D. I and II
E. II and III
F. I and III
G. I, II and III (all of them)
2m
Chapter 28 Solutions
Physics for Scientists and Engineers, Technology Update (No access codes included)
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DC Series circuits explained - The basics working principle; Author: The Engineering Mindset;https://www.youtube.com/watch?v=VV6tZ3Aqfuc;License: Standard YouTube License, CC-BY