Students have plenty of experience using everyday household appliances that rely on electric circuits for their operation ( torches, mobile phones, iPods). They very likely have developed a sense that you need a battery or power switch to be turned on to make things ‘work’, and that batteries can go ‘flat’. They tend to think of electric circuits as involving something they call ‘current’ or ‘energy’ or ‘electricity’ or ‘voltage’, all labels which they often use interchangeably.
molten material is magma or lava
in the story, ali baba is a poor woodcutter who discovers the secret of a thieves' den, entered with the phrase "open sesame". the thieves learn this and try to kill ali baba, but ali baba's faithful slave-girl foils their plots. ali baba gives his son to her in marriage and keeps the secret of the treasure.