Q.
In a meter bridge two gaps in the metallic strip are connected by 3Ω and 9Ω resistors. What should be the value of shunt that needs to be added to 9Ω resistor to shift balancing point by 25cm ?
(c) The given situation is shown below, Suppose bridge is balanced at a distance / from one end.
Initially in balance condition, l3=100−l9 ⇒l=25cm
When a shunt S′Ω is connected to 9Ω resistor balance point shifts by 25cm.
So, new balance length =25+25=50cm
As meter bridge is balanced at centre point. This means resistances of left and right gap are equal. ⇒3=9+S9S ⇒S=4.5Ω