Question

A battery lights a bulb. Describe the energy changes in the process.

Answer 1

Hint: A battery stores energy in the form of chemical energy that is present due to the chemicals inside it to react. A bulb uses electrical energy to light up its surroundings.

Complete step by step answer
A battery has chemicals inside it which can react with each other and generate electricity through the flow of electrons. Hence when a battery is connected with a bulb, its chemical potential energy is converted into electrical energy.
This electrical energy is then transferred to the circuit containing the bulb. Inside the bulb, there is a mechanism to convert electrical energy into light energy. In the process, heat energy is also generated. This is the reason why when we operate a bulb, it grows hot after some time. Different kinds of bulbs use different mechanisms to convert electrical energy into light energy.
Hence to summarize, the energy change in the process will be, Chemical energy $\to$ Electrical energy $\to$ Light and heat energy.

Note
When the current is following in the circuit, there will be energy losses due to the different resistances in the circuit too. However, according to the law of conservation of energy, energy can only be transferred from one form to another i.e. it cannot be created or destroyed. So, if we were able to measure the heat loss energy as well as the emitted light energy, we’d find that the net energy supplied by the battery is equal to the sum of all the converted energy and the heat energy losses.