A photocell is any of a wide range of sensors that react based on the presence of light or electromagnetic energy. They can be found in many different forms, from solar panels that use light to generate electricity, to photoresistors, which shift in resistance based on how much light is present.
Bond prices and yields are like a seesaw: when bond yields go up, prices go down, and when bond yields go down, prices go up. In other words, a move in the 10-year Treasury yield from 2.2% to 2.6% indicates negative market conditions, while a move from 2.6% to 2.2% indicates positive market performance.
The yield of a bond is the discount rate at which the present value of future cash flows is equal to the current price of the bond. 1  Let's say that a bond is selling at $120 and pays an annual coupon of $10 for ten years (ten-year maturity) and then pays a principal of $100.