Question

Example 282 Matching the Load the maximum power matches te Figure 2.28 Orat d agram of of- s connected to an of retance Solution e power delivered to the load resistance is equal to I2R, where I is given by Equation 28.3 n P is plotted versus R as in Figure 28.3, we find that P a maximum value of emfy4r at R r, when R is large, is very little current, so that the power I R delivered to the load resistor is smal. When R is small, the current is large and e is significant loss of power I2r as energy is delivered to the internal resistance. When R r, these effects balance to give a ximum transfer of power. can also prove that the power maximizes at R rby ifferentiating P with respect to R, setting the result equal to zero, nd solving for R Figure 28.3 Graph of the power delivered by a battery to a load resistor of resistance R as a function of R. The power delivered to the resistor is a maximum when the load resistance equals the internal resistance of the Exercise 282 Hints: Getting Started1 'm Stuck (a) At this condition for maximum transfer (from power supply to the load resistor), what is the efficiency of the circuit? (That is, the power dissipated by the load resistor, divided by the total power delivered by the battery.) (b) With R 7r, what is the efficiency?

Answer 1

2 叉, γ So eFrueho r eb-@re-eur ?Y %-0.875