As I'm a lecturer of physics, I've to take some practical classes. There are two labratory rooms for physics. Some of the practicals that are to be performed by students need power supply. But now a days it has become a common problem that students do not get power supply during their lab. Any theory class can be coducted without power supply but practical classes has to be stopped in that situation. Today I've to stopped my practical classes after waiting half time of the class. In this situation students are suffering. They can not complete their all practicals. So when power supply is off there should be back up power supply at least at all practical laboratories.