NEET-XII-Physics
39: Alternating Current
- #16-aWhat frequency should be chosen to maximise the current in the circuit? (b) What is the value of this maximum current? (b) What is the value of this maximum current? (b) What is the value of this maximum current?Ans : In an LCR circuit, current is maximum when reactance is minimum, which occurs at resonance, i.e. when capacitive reactance becomes equal to the inductive reactance,i.e.
XL = XC
`` \Rightarrow \omega L=\frac{1}{\omega C}``
`` \Rightarrow {\omega }^{2}=\frac{1}{LC}=\frac{1}{2\times 18\times {10}^{-6}}``
`` \Rightarrow {\omega }^{2}=\frac{{10}^{6}}{36}``
`` \Rightarrow \omega =\frac{{10}^{3}}{6}``
`` \Rightarrow 2\,\mathrm{\,\pi \,}f=\frac{{10}^{3}}{6}``
`` \Rightarrow f=\frac{1000}{6\times 2\,\mathrm{\,\pi \,}}=26.539\,\mathrm{\,Hz\,}``
`` =27\,\mathrm{\,Hz\,}`` (b) At resonance, reactance is minimum.
Minimum Reactance, Z = R
Maximum current (I) is given by,
`` I=\frac{E}{R}``
`` \Rightarrow I\mathit{=}\frac{20}{10\times {10}^{3}}``
`` \Rightarrow I=\frac{2\,\mathrm{\,A\,}}{{10}^{3}}=2\,\mathrm{\,mA\,}``
Page No 330: (b) At resonance, reactance is minimum.
Minimum Reactance, Z = R
Maximum current (I) is given by,
`` I=\frac{E}{R}``
`` \Rightarrow I\mathit{=}\frac{20}{10\times {10}^{3}}``
`` \Rightarrow I=\frac{2\,\mathrm{\,A\,}}{{10}^{3}}=2\,\mathrm{\,mA\,}``
Page No 330: (b) At resonance, reactance is minimum.
Minimum Reactance, Z = R
Maximum current (I) is given by,
`` I=\frac{E}{R}``
`` \Rightarrow I\mathit{=}\frac{20}{10\times {10}^{3}}``
`` \Rightarrow I=\frac{2\,\mathrm{\,A\,}}{{10}^{3}}=2\,\mathrm{\,mA\,}``
Page No 330:
- #16-bWhat is the value of this maximum current?Ans : At resonance, reactance is minimum.
Minimum Reactance, Z = R
Maximum current (I) is given by,
`` I=\frac{E}{R}``
`` \Rightarrow I\mathit{=}\frac{20}{10\times {10}^{3}}``
`` \Rightarrow I=\frac{2\,\mathrm{\,A\,}}{{10}^{3}}=2\,\mathrm{\,mA\,}``
Page No 330: