Exercise EE1-04.02 – Power of a resistor

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

Relates to EE1-04 Resistance

Task

a) What maximum current $I_{max}$ may flow through a resistor $R=485\Omega$ that is rated for a maximum permissible power $P_{max}=10\mathrm{W}$? What voltage then drops across the resistor?

b) What maximum power $P_{max}$ must a resistor at least be rated for if, at an applied voltage $U=42\mathrm{V}$, a current $I=0.23\mathrm{A}$ flows through it?

c) What maximum voltage $U_{max}$ may be applied to a resistor through which a current $I=130\mathrm{mA}$ flows if it is rated for a maximum power $P_{max}=250\mathrm{mW}$?

Solution

a) $0.14\mathrm{A}$; $70\mathrm{V}$
b) $10\mathrm{W}$
c) $1.92\mathrm{V}$

▶️ Full worked solution