Question

What is a button cell? Write it 's two uses.

Answer 1

A watch battery or button cell is a small single cell battery shaped as a squat cylinder typically 5 to 25 mm in diameter and 1 to 6 mm high—like a button on a garment, hence the name It is used for calculators and wrist watches...both analog and digital.

Answer 2

A button cell is a very small battery. A good example is the type found in most modern watches. This type of battery is often used in camcorders as backup batteries. They ensure that the date and time are held in memory even when the rechargeable batteries are removed.

The two uses are :- 
1. It is used in watches as battery.
2. It is also used as battery in some toys.