A toaster converts electrical energy into heat energy. When you plug a toaster into an electrical outlet and turn it on, the electrical energy flows through the heating elements inside the toaster. These heating elements have a high electrical resistance, which causes them to heat up quickly. As they heat up, they transfer this heat energy to the slices of bread or other food items placed inside the toaster, toasting or heating them in the process. So, the primary conversion that takes place in a toaster is from electrical energy to heat energy.