A search-and-rescue helicopter hovering above the sea is used to lift a casualty using a metal winch cable.
Explain how the hovering helicopter becomes electrically charged.
Why does this charge remain on the metal fuselage of the helicopter while it is hovering?
Suggest why it is particularly dangerous for the helicopter and its winch line to accumulate an electrical charge during a rescue operation.
To prevent this danger, a conductive static discharge cable is lowered from the helicopter to touch the water before the rescue crew or winch hook makes contact with anyone on the ground. Explain how this cable prevents the helicopter from remaining charged.