Answer the following question given this paragraph: 

Figure below shows a diagram of a simple doorbell. Like most doorbells, it has a button located by the front door. Pressing the button causes two electric contacts to come together and complete an electric circuit. In other words, the button is a switch. The circuit is also connected to a voltage source, an electromagnet, and the clapper of a bell. When current flows through the circuit, the electromagnet turns on, and its magnetic field attracts the clapper. This causes the clapper to hit the bell, making it ring. Because the clapper is part of the circuit, when it moves to strike the bell, it breaks the circuit. Without current flowing through the circuit, the electromagnet turns off. The clapper returns to its original position, which closes the circuit again and turns the electromagnet back on. The electromagnet again attracts the clapper, which hits the bell once more. This sequence of events keeps repeating as long as the button by the front door is being pressed.


Q: When two electric contacts come together it completes a what?


A:
cricuit