Adidas is developing a soccer ball containing what that sends a radio signal to the referee's watch when it crosses the goal line?

probably an electric device that has a sensor inside as well as air

It has to touch a player in order for it to be counted as a goal.

No. All parts of the ball must be past all parts of the line.

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Also known as the end line, the goal line is the line that runs the width of the field. It runs across the front of the goal and when the ball passes the end line within the goal posts, a goal is...