Inside a toaster, electrical energy is primarily converted into heat energy. When you plug in a toaster and turn it on, electricity flows through the heating elements inside the toaster. These heating elements are usually made of nichrome wire, which has a high electrical resistance.
As electricity passes through the heating elements, they become very hot due to the resistance they offer to the electrical current. The heat generated by the heating elements is then transferred to the slices of bread or other food items placed inside the toaster. This causes the food to toast or brown as the sugars and proteins in the food undergo a chemical reaction called the Maillard reaction, resulting in the characteristic toasted flavor and texture.
It's important to note that there may be other minor energy conversions in a toaster, such as some electrical energy being converted into light energy (in the form of the glowing heating elements), or mechanical energy in the form of the toaster's lever mechanism used to lower and raise the bread. However, the dominant energy conversion in a toaster is from electrical energy to heat energy, which is used for toasting the food.