(Take $\left.g=10\,ms ^{-2}\right)$
$\frac{10^{4} \times 0.5}{100}= n$
$100 \times 0.5= n$
$n =50$

$[1]$ battery emf is increased
$[2]$ all resistances are increased by $10\,ohms$
$[3]$ all resistances are made five times
$[4]$ the battery and the galvanometer are interchanged
