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.
The production costs for making a billboard advertisement are relatively minimal. Printing an advertisement on vinyl for a bulletin billboard (almost 700 square feet of material) will cost around $500. To ballpark production costs per billboard, take the area of the billboard in square feet and multiply it by $0.80.ost Per Billboard: $2,500 per billboard (rate for the purchase 28 billboards). If you wanted to buy billboard advertising in Atlanta, Georgia for a year, the annual cost would be the (number of months) times (the minimum number of billboards) times (the cost per billboard).