During one of my labs we were using circuits. I connected a 9V battery in parallel with a 2.kΏ resistor and a multimeter. I meaured the current across the circuit and noticed it went really high at the beginning (about 30mA) and then it slowly went down and the battery became really hot and unusable. Why did that happened? I've been trying to find why the battery would get hot and stop working. Any help?