The device for measuring the current or emf is connected within the circuit of the thermocouple. It measures the amount of emf flowing through the circuit due to the two junctions of the two dissimilar metals maintained at different temperatures. In figure 2 the two junctions of the thermocouple and the device used for measurement of emf (potentiometer) are shown.
I think that this is what advertisers are shooting for when they pay the big price to get their ads up there. Regular billboards are just as effective as ever, even though there are now digital billboards being made that can have multiple ads on them and switch between them every few seconds.
I wanted to get into this business... I have found that Outdoor Billboards cost an investment of about $150,000 to $200,000 for a single face billboard, the potential net profit can be between $125,000 and $360,000 per year! With ads costing your clients $1200 per week for each ad. If you have the capital...