It measures the strength of the current (7)
I believe the answer is:
ammeter
This could be a double definition.
'it measures the strength' is the first definition.
The definition suggests a singular noun which matches the answer.
'current' is the second definition.
I know that 'current' relates to this answer. I also know that both the answer and definition are singular nouns
'of the' acts as a link.
Can you help me to learn more?
(Other definitions for ammeter that I've seen before include "Current-measuring instrument" , "Current-measurer" , "Instrument that measures electric current." , "Device that measures the flow of electrical current" , "Instrument measuring electrical current" .)