Well, firstly 6 joules is a very low number for a dryer (impossibly low). But here is how you'd do it with a more realistic number:
Energy is the power consumed multiplied by the time over which it is consumed:
[tex]E=Pt \\ P= \frac{E}{t} = \frac{6J}{180s} =0.033W[/tex]
This power is current time voltage
[tex]P=VI =220V \times I=0.033W \\ I= \frac{0.033W}{220V}=0.152mA [/tex]
As you can see this current is very low by any household appliance standard, let alone an energy-hungry dryer! Are you sure it's not something more like
6×10⁵ J for the energy?
