A magnet was inserted into a wire ring connected to a ballistic galvanometer of 30 ohm resistance, this causing 20 division deflection of the galvonometer printer. What magnetic flux passes through the pole pices of the magnet. If the galvonometer constant is `3 xx 10^(-5)"C/div"?` Neglect the resistance of the resistance of the ring and of the leads.

Answer

`1.8 xx 10^(-2). Wb`

Explanation

The induced e.m.f. is `delta=-(triangle Psi)/(trianglet)=(Psi)/(trianglet)` since initially the magnetic flux, through the ring is zero. The change flowing through the circuit is `|triangle|=epsi/R triangle t=(Psi)/R`
It is equal to the galvonometer constant multiplied by the number of scale divisions q=CN.