Answer
$ {V_{T}} $ $=$ $ 7 $ $ volts $
$ {P_{L}} $ $=$ $ 7 $ $ mWatts $
$ e $ = $0.5833$ or $58.33$ $percent$
Work Step by Step
To find the value of the series resistance:
$ {R_{T}} $ $=$ $ {R_{s}} $ + $ {R_{L}} $
$ {R_{T}} $ $=$ $ 5 $ $komhs$ + $ 7 $ $komhs$
$ {R_{T}} $ $=$ $ 12 $ $komhs$
Using $ {R_{T}} $ and $ {V_{s}} $, we can now determine the value of $ {I_{T}} $ using Ohms' law
$ {I_{T}} $ $=$ $\frac{V_{s}}{R_{T}}$
$ {I_{T}} $ $=$ $\frac{12}{12\times10^{3}}$
$ {I_{T}} $ $=$ $ 1 $ $ mA $
To find $ {V_{T}} $, we need to find $ {V_{L}} $ because they are equal.
$ {V_{T}} $ $=$ $ {V_{L}} $ $=$ $ {I_{T}\times{R_{L}}}$
$ {V_{T}} $ $=$ $ 1\times10^{-3}\times{7\times10^{3}}$
$ {V_{T}} $ $=$ $ 7 $ $ volts $
To find the power absorbed by the load:
$ {P_{L}} $ $=$ $ {V_{L}\times{I_{T}}}$
$ {P_{L}} $ $=$ $7\times1\times10^{-3}$
$ {P_{L}} $ $=$ $ 7 $ $ mWatts $
To find the total power of the circuit:
$ {P_{T}} $ $=$ $ {V_{s}\times{I_{T}}}$
$ {P_{T}} $ $=$ $12\times1\times10^{-3}$
$ {P_{T}} $ $=$ $ 12 $ $ mWatts $
To find the efficiency of the circuit:
$ e $ $=$ $\frac{P_{L}}{P_{T}}$
$ e $ $=$ $\frac{7\times10^{-3}}{12\times10^{-3}}$
$ e $ = $0.5833$ or $58.33$ $percent$
