Question

A student has a set of 176 ohm resistor how many resistor of 176 ohm he will connect in parallel with 220 volt supply so that the ommeter connected by him reads 5a on the scale

Answer 1

As V= 220V and I = 5A

So Re = 220/5 = 44ohm (effective resistance)

Now for parallel connected resistance we have,

1/Re = 1/R+1/R+.....

or 1/Re = n/R

n = 1/Re× R

or n = 1/44×176 = 4

Ans: So 4 resistors of 176ohm must be joined parallel for effective resistance of 44 ohm.