To solve the problem, we need to identify which device converts mechanical energy into electrical energy.
1. Understanding Energy Conversions:
- A motor converts electrical energy into mechanical energy.
- A battery stores and provides chemical energy converted to electrical energy.
- A switch simply opens or closes an electrical circuit; it doesn’t convert energy.
- A generator converts mechanical energy into electrical energy using electromagnetic induction.
2. Correct Option:
The device that performs the required conversion is the generator.
Final Answer:
The correct answer is \({\text{Generator}} \).