A Microwave

Affordances Nobs affords turning

Handle affords opening

Inside plate affords removal

The plug affords connecting

Mappings Mapping of power nob controls clear

images with a diagram at the bottom clearly indicating which image refers to what.

Mappings of the timer nob controls indicated the unit of time

Physical Constraints The size of the plate inside the microwave

is a physical constraint of the size of an object that can be placed in the microwave.

The plug stops you from connecting it upside down with the top part. However this is the same for all electronic device.

The controls have a physical constraint to not allow an object to be placed in the microwave for longer than 30 minutes

Conventions The time nob using the cultural convention

for the unit of time. It does not state that it is in minutes. The minute is the general culturally accepted unit of time for nearly all countries.

Mappings of the power nob also used the cultural conventions to describe the power. Low, medium and high are culturally accepted however in other countries this may differ.

Uses cultural conventions for what can be placed in the microwave there is no indication.

Where does the object fail in anyway to be obvious to use?

Firstly the microwave does not state the wattage or power of it on the front it took a few minutes to realise it was printed on the back. If this was printed on the front it would be much more obvious.

Another problem is that it does not state any materials that cannot be placed inside the microwave although It uses cultural conventions assuming metal and plastic won’t be placed inside. This could have been more obvious by stating it on the front. Whats to stop someone placing a plastic cup inside?

The units of time are not obvious again relying on cultural conventions this could have been made more obvious by putting the units of time below.