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.
1 Billboard advertising costs can be different depending on the location of the billboard. 2  Areas with higher traffic can cost more compared to a billboard that is placed in an area which generates little traffic. The price can also increase depending on the duration of the contract you sign with the advertising company. 2  Because of these different factors, the price of billboard advertising has a very wide range; it can cost from $1,500 to as much as $100,000 per month.