Why is electrical energy transmitted at high voltage from a distance power generating station?

What is step up and step down transformer? To transfer electric energy from generating station initially step up transformer is used. Why?

A lamp consumes 1000J of electrical energy in 10s. What is the power?

Why heat energy is produced, when electric current passes through a resistance wire?

Why is an insulator sometimes called a dielectric? What is the main difference between free and bound charge? Generally one of the two plates of a Capacitor System is earthed, why? Derive the expression for the energy stored in a charged capacitor.