I cannot find the answer anywhere on the reading or notes.

Which of the following is a primary function of an adaptor that you plug into an ordinary electrical socket?
It converts AC input to DC output.
It converts AC input to AC output of a different frequency.
It converts DC input to AC output.
It converts AC input to AC output with a different maximum voltage.

well, the wall socket has AC

The adaptor might convert to DC or affect the voltage.
Usually changing the voltage of AC is the function of a transformer.
So, I'd have to go with #1.

It will not generally affect the frequency of AC, and it certainly cannot convert from DC, since the wall outlet does not provide DC.

To find the answer to this question, we can start by understanding what an adaptor does when it is plugged into an ordinary electrical socket.

First, let's break down the options and analyze each one:

1. "It converts AC input to DC output."
2. "It converts AC input to AC output of a different frequency."
3. "It converts DC input to AC output."
4. "It converts AC input to AC output with a different maximum voltage."

Based on the definition of an adaptor, we know that its primary function is to allow a device to be powered by an electrical socket. Adaptors typically convert the voltage or improve the compatibility between the electrical socket and the device being powered.

To eliminate the incorrect options, we can analyze the given statements:

Option 1 is incorrect because adaptors usually convert the voltage but do not typically convert AC input to DC output.

Option 2 is also incorrect as adaptors are not meant to change the frequency of the input.

Option 3 is not accurate either because adaptors typically do not convert DC input to AC output. Most devices that use an adaptor require AC input.

This leaves us with option 4: "It converts AC input to AC output with a different maximum voltage." This option is the most likely choice because adaptors often change the voltage of the AC input to match the requirements of the device being powered.

Therefore, based on the analysis of the given options and the functionality of adaptors, the correct answer is: It converts AC input to AC output with a different maximum voltage.