Power Transfer

• The internal Impedance of a voltage source forms a voltage divider with a connected load, the voltage across which is,

• The power delivered to the load is,

• Maximum power ($P=V_{source}^2/4Z_{source}$) is transferred when $Z_{load}=Z_{source}$
• Minimum power ($P=0$) is transferred when $R_{load}$ = 0 or $\mathrm{\infty }$

Notes

• Known as Maximum Power Transfer Theorem
• Only 50% of a source's power can be transferred to a load
• Can be applied to a Current Source with Norton's and Thevenin's Theorem