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--- electrical_engineering_1:task_rj0r6j4apumukrj6_with_calculation [2023/03/31 07:41] – mexleadmin
+++ electrical_engineering_1:task_rj0r6j4apumukrj6_with_calculation [Unbekanntes Datum] (aktuell) – gelöscht - Externe Bearbeitung (Unbekanntes Datum) 127.0.0.1
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-{{tag>resistivity power exam_ee1_WS2022}}
-{{include_n>100}}
-#@TaskTitle_HTML@#~~#@ee1_taskctr.#~~  Resistance of a Wire by Resistivity  \\ <fs medium>(written test, approx. 6 % of a 60-minute written test, WS2022)</fs> #@TaskText_HTML@#
-A heating element made of a Nichrome wire with a round cross-section is used in an electric oven. \\
-Nichrome is a common Nickel Chromium alloy for heating elements. \\
-The Nichrome wire has a resistivity of $1.10\cdot 10^{-6} ~\Omega \rm{m}$. \\
-The heating element is $3 ~\rm{m}$ long and has a diameter of $3.57 ~\rm{mm}$. \\ \\
-. Calculate the resistance $R$ of the heating element.
-#@PathBegin_HTML~1~@#
-\begin{align*}
-R &= \rho \cdot \frac{l}{A} && | \text{with  } A = r^2 \cdot \pi = \frac{1}{4} d^2 \cdot \pi \\
-R &= \rho \cdot \frac{4 \cdot l}{d^2 \cdot \pi} && \\
-R &= 1.10\cdot 10^{-6} ~\Omega \rm{m} \cdot \frac{4 \cdot 3~\rm{m}}{(3.57\cdot 10^{-3}~\rm{m})^2 \cdot \pi} && \\
-\end{align*}
-#@PathEnd_HTML~1~@#
-#@ResultBegin_HTML~1~@#
-\begin{align*}
-R &= 0.33 ~\Omega \\
-\end{align*}
-#@ResultEnd_HTML~1~@#
-. The heating element is used to heat the oven to a temperature of $180~°\rm{C}$. For this, a power dissipation (= heat flow) of $P=40 ~\rm{W}$ is necessary. \\ Calculate the current $I$ needed to operate it.
-#@PathBegin_HTML~2~@#
-\begin{align*}
-P = U \cdot I = R \cdot I^2  \quad \rightarrow \quad I= \sqrt{\frac{P}{R}} = \sqrt{\frac{40 ~\rm{W}}{0.33 ~\Omega}}
-\end{align*}
-#@PathEnd_HTML~2~@#
-#@ResultBegin_HTML~2~@#
-\begin{align*}
-I = 11 ~\rm{A}
-#@ResultEnd_HTML~2~@#
-#@TaskEnd_HTML@#

resistivity power exam ee1 ws2022