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| 2023/10/05 08:55 | resistivity power exam_ee1_ss2023 Resistivity and temperature dependent Resistance (written test, approx. 7 % of a 60-minute written test, SS2023) The resistance of the dielectric material of a film capacitor has to be calculated. The given film capacitor has an internal surface of $A=100 ~\rm dm^2$$d=0.8 ~\rm μm$$\rho_{\rm PP}(20 ~\rm °C)=10^{17} ~\Omega m$$20 ~\rm °C$$55 ~\rm °C$$\alpha =-0.048 ~\rm 1/K$$\beta=+0.00057 ~\rm 1/K^2$$20 ~\rm °C$\begin{align*} R(20 ~\rm °C) &= \rho\c… | ||
| 2023/02/11 22:24 | Tim Fischer | resistivity power exam_ee1_ws2022 Resistance of a Wire by Resistivity (written test, approx. 6 % of a 60-minute written test, WS2022) A heating element made of a Nichrome wire with a round cross-section is used in an electric oven. Nichrome is a common Nickel Chromium alloy for heating elements.$1.10\cdot 10^{-6} ~\Omega \rm{m}$$3 ~\rm{m}$$3.57 ~\rm{mm}$$R$\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 \… |