For lamp $$I=cfrac { 5 }{ 20 } 0.25A;R=cfrac { 20 }{ 0.25 } =80Omega quad $$ Current through the lamp should be $$0.25A$$ (a) when condenser $$C$$ is placed in series $$quad i=cfrac { 200 }{ sqrt { { R }^{ 2 }+{ left( cfrac { 1 }{ omega C }  \right)  }^{ 2 } }  } =0.25$$ putting the value of $$omega =2pi imes 50$$ $$ herefore C=4.0mu F$$ (b) when inductor is used $$I=cfrac { 200 }{ sqrt { { R }^{ 2 }+{ left( omega L \right)  }^{ 2 } }  } =0.25Rightarrow L=2.53H$$ (c) when resistance is used $$I=cfrac { 200 }{ R+r } =0.25Rightarrow r=720Omega quad $$