Hey guys. For my chemistry practical we did a galvanic cell investigation, but in one electrolyte solution (NaCL). The electrodes were graphite and zinc. Can someone please explain how this even produces a reading on the voltmeter? There is a picture below?
![chem2.4.11.png](/data/attachments/22/22396-35c99df6b0b35e1c4f9a1dd3c7af157f.jpg)