Effects of these habits are : -
1. Wastage of electricity.
2. Leads to Shortage of electricity creating problems to people of urban areas and mostly to the people of rural areas.
3. Due to this, government is forced to start powercut.
Measures that should be taken to prevent this are : -
1. Teachers must be strict and responsible towards students.
2. Students must also be responsible to switch off the lights and fans.
3. Every student must look at the switch of lights and fans while moving out of class so that the wastage can be prevented.
Hope you are satisfied with the answer. My classmates also got the topic and i helped them with this.