10
10
100
106
V=IRRf=Vf/If=0.7/(10⁻⁵)=7×10⁴In the similar way,0.75/15=5×10⁴and0.8/20=4×10⁴∴Rf=0.7/(4.75(10⁻⁵))=10andRb=VB/IB=10/10⁻⁷=10⁷∴Rf/Rb=10/10⁷=10⁻⁶