Yes, coal and petroleum products are used in the production of electricity. Which runs the electrical appliances at Salma's home. As coal and petroleum are non-renewable sources i.e. once they are used, they cannot be replaced. So, if we use coal and petroleum excessively then a point of time may come when it will not be available at all, which can create a crisis of electric energy. That's why Salma tries to save electricity, which can eventually save coal and petroleum.