Why are the spokes in motorcycle wheels not arranged perpendicular to the rim but at an angle?Ashish Sundar, Cochin, KeralaHow are sparks generated from a lighter which is used to light a gas stove?K. Sreenath Suman Kumar, Kurnool, Andhra PradeshWhy are the wheels of a train edged out from the inner side and not from outside?P.S. Dheenadayalan, BangaloreReaders can send questions/answers on science and technology for the Question Corneralong with their names and address to the following email id: questioncorner@thehindu.co.in or to The Editor, The Hindu (Science and Technology), 859-860, Anna Salai, Chennai 600 002.