What are the risks of putting a 2-pronged plug into a 3-prong outlet?
A 2-prong plug connects with the hot and neutral wires. The top hole in a three prog outlet connects to the ground wire; small appliances usually don’t need a ground wire.
The 3rd, earth connection, is required for devices that require an earth. If your device originally comes with the 2-connector plug, it doesn’t need earth, so there is no problem connecting it to the 3-connection outlet.
The other way round can be a problem. If you cut away the earth connection from a device that originally came with the earth plug, & then connect it to a socket, it can cause electrocutions, fire, or if it is a delicate device that needs a stable electric circuit (measuring device etc.), the missing earth can cause instability & faulty measurements.
The 3-prong outlet is a backwards compatible outlet. The 3rd prong is usually connected to ground (basically a physical wire connected to either a copper stake driven 6 feet into the ground or to your home’s copper water pipe. It’s designed to be connected to the chassis of a higher voltage appliance, such as the old cathode ray tube TV sets for that when a person is working on it live, they connect to ground so that if they somehow accidentally touched the live circuit, it goes to ground instead of through your heart. It was designed to provide some minor safety to a person. You can still get electricity going through whatever item goes to ground, be it a screwdriver or your hand. It mainly reduces the chance that it goes through your heart.
Modern 3rd prong outlets include GFCI circuits, and is basically an additional protection to shut of the circuit at the socket if any electricity leaks to ground. Ground by itself protects users from a shock to the heart, but it does not stop electricity from flowing. It also doesn’t protect you if you’re in a bathtub that has pipes also going to ground. GFCI will protect users better than just plain ground, since it detects the fault and shut of the circuit.