Question

A galvanometer having a coil resistance of $60\, \Omega$ shows full scale deflection when a current of $1.0\, amp$ passes through it. It can be converted into an ammeter to read currents upto $5.0\, amp$ by

• A. putting in series a resistance of $15\, \Omega$
• B. putting in series a resistance of $240\, \Omega$
• C. putting in parallel a resistance of $15\, \Omega$
• D. putting in parallel a resistance of $240\, \Omega$

Answer 1

Answer: (C)

putting in parallel a resistance of $15\, \Omega$

Answer 2

$Ig =1.0 A,\, G =60\, q,\, I =5.0\, A$
$S =\frac{ I _{ g }}{ I - I _{ g }} G$
$G =\frac{1.0}{5.0-1.0}=60$
$=15\, \Omega$ in parallel