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.
Switch S in in the figure is closed at time t = 0, to begin charging an initially uncharged capacitor of capacitance C = 17.2 μF through a resistor of resistance R = 21.2 Ω. At what time is the potential across the capacitor equal to that across the resistor?
A capacitor that is initially uncharged is connected in series with a resistor and an emf source with EEEMF = 110 VV and negligible internal resistance. Just after the circuit is completed, the current through the resistor is 6.6×10−5 AA. The time constant for the circuit is 4.3 s.What is the resistance of the resistor?
At time t = 0, an RC circuit consists of a 14.0-V emf device, a 54.0-Ω resistor, and a 148.0-µF capacitor that is fully charged. The switch is thrown so that the capacitor begins to discharge.
Time constant of the circuit is 0.007992s
How much charge is stored by the capacitor at t = 0.5?, 2?, and 4??
Chapter 28 Solutions
Physics for Scientists and Engineers, Technology Update, Hybrid Edition (with Enhanced WebAssign Multi-Term LOE Printed Access Card for Physics)
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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