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| 1. |
Show that the force on each plate of a parallel plate capacitor has a magnitude equal to (1)/(2)QE, where Q is the charge on the capacitor and E is the magnitude of electric field between the plates. Explain the origin of the factor (1)/(2). |
| Answer» <html><body><p></p>Solution :Let the application of force <a href="https://interviewquestions.tuteehub.com/tag/f-455800" style="font-weight:bold;" target="_blank" title="Click to know more about F">F</a> increases the distance between the plates by `trianglex`. <br/> Work done by the external force `=F*triangle x` <br/> This increases the energy. <br/> Energy <a href="https://interviewquestions.tuteehub.com/tag/density-17451" style="font-weight:bold;" target="_blank" title="Click to know more about DENSITY">DENSITY</a> = u <br/> So, <a href="https://interviewquestions.tuteehub.com/tag/increase-1040383" style="font-weight:bold;" target="_blank" title="Click to know more about INCREASE">INCREASE</a> in energy `= u(alpha triangle x) ""[alpha = " area of the plate "]` <br/> `:. F* trianglex = u alpha "" triangle x " or, " F = u alpha` <br/> `:. F = (1)/(<a href="https://interviewquestions.tuteehub.com/tag/2-283658" style="font-weight:bold;" target="_blank" title="Click to know more about 2">2</a>)in_0 E^2* alpha ""[:. u = (1)/(2) in_0E^2]` <br/> `:. F = (1)/(2) in_0 alpha E*E = (1)/(2) <a href="https://interviewquestions.tuteehub.com/tag/qe-610319" style="font-weight:bold;" target="_blank" title="Click to know more about QE">QE</a>` <br/> The factor `(1)/(2)` arises in this relation due to the fact that average `(E )/(2) " of "0` and E is taken.</body></html> | |