1. The problem statement, all variables and given/known data The dynamo (generator) of a push bike is made to turn when the bicycle wheel turns. The generator provides energy to light the bicycle’s lamp. Would a cyclist coast further if the lamp connected to the generator were turned on or off? Why? 2. Relevant equations 3. The attempt at a solution If on then power is dissipated via P=I^2R so some energy from the peddler is given to powering the light. If off then no power is lost and the generator will turn by itself (although some energy is lost to friction which must come from the peddler) after it has turned a cycle. This is because potentials get accumulated on the ends of the disconnected ciruit and can be reversed to allow for the induced emf in direction and magnitude. Hence if the peddler supplies the same amount of energy as the first case of lamp turned on then a lot more percentage of energy is turned into motion of the bike. So coast further with lamp turned off.