Exercise EE1-03.01 – Voltage drop across the internal resistance

Prof. Dr. Thorsten Jungmann (last updated 2025-10-27)

Relates to EE1-03 Sources

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Task

On a real voltage source, you measure a terminal voltage of $U_0=10\mathrm{V}$ with no load connected. You now connect a resistive load and find that the terminal voltage drops by $2\%$. You look at the load and see the marking $U_{\mathrm{rated}}=20\mathrm{V}$, $P_{\mathrm{rated}}=4.0\mathrm{W}$.

a) Calculate the resistance of the connected load.
b) Determine the terminal voltage under load.
c) Determine the value of the internal resistance of the voltage source.
d) What power is dissipated in the load?

Solution

a) $100\Omega$
b) $9.8\mathrm{V}$
c) $2.0\Omega$
d) $0.96\mathrm{W}$

▶️ Full worked solution