Put switch on. Rotate the variac, until the lamp glows. Take reading for all the instruments at the striking voltage.The Wattmeter now indicates power of mode Next change the switch to mode and take reading for all instruments. The Wattmeter now indicates power for what. Increase voltage to value v and take reading for all instruments.The Wattmeter now indicates power of mode Again change position of switch & take wattmeter reading. Similarly keep on increasing voltage by 10 v till 230 v is reached and take wattmeter reading for both position of switch. Now rotate variac until it reaches 230 v,then take reading for all instruments The fluorescent lamp strikes at approx 180 v and extinguishes at a much lower voltage i.e, 138 v.This is because the neon atoms need a large voltage to get ionized but remain changed till a considerably lower voltage. The fluorescent lamp with electronic ballast strikes at a much lower voltage compared to the one with inductive ballast.The total power consumption at 230 v is also lower in this case.