What is the function of the ELEC RH ESS switch on the Emergency Panel?

The function of the ELEC RH ESS switch on the Emergency Panel is to isolate the right essential bus (RH ESS BUS) and force the connection of battery 2. This switch is crucial in emergency situations where it's necessary to ensure that the essential electrical systems maintain power when the primary power sources are compromised. Isolating the RH ESS BUS allows for a dedicated power supply from battery 2, which can be critical for maintaining the operation of vital instruments and systems during an emergency scenario.

The other options pertain to functions that are not directly associated with the ELEC RH ESS switch. Supplying power to the RH MAIN bus could imply utilizing different power sources or systems, which does not align with the specific isolation and battery connection role of the ELEC RH ESS switch. Connecting to ground service power is a function primarily related to powering the aircraft while on the ground without using internal power sources, which is separate from the operation of the emergency panel. Activating emergency hydraulic systems deals with hydraulic power rather than electrical systems, further distinguishing these functions from that of the ELEC RH ESS switch.