Farmer Bir Virk tapped the iPad mounted beside his tractor’s steering wheel and switched the vehicle to automatic mode. The machine moved forward and began harvesting potatoes on its own in the fields of Karnal, a city in northern India.Some 145 kilometers (90 miles) away in the country's capital of New Delhi, educator Swetank Pandey employed similar automation at his coaching academy. He used algorithms to scan and grade handwritten exam papers from candidates for India’s competitive civil services.In both cases, the same invisible hand was at work: artificial intelligence.From farms to classrooms, AI is fast emerging as a tool…