• # question_answer The following observations were taken while comparing the e.m.f s of two primary cells using a potentiometer. Balance point when ${{E}_{1}}$ (Leclanche cell) in the circuit (${{\ell }_{1}}$in cm) $=350$ Balance point when ${{E}_{2}}$ (Daniel cell) is the circuit (${{\ell }_{2}}$ in cm) $=275$ The ratio $({{E}_{1}}/{{E}_{2}})$ of emfs is approximately A)  $1.30$                        B)  $1.17$C)  $1.27$                        D)  $1.5$

${{f}_{c}}=9\sqrt{{{N}_{m}}}=9\times \sqrt{9\times {{10}^{10}}}$ $=2.7\times {{10}^{6}}Hz=2.7\,MHz$