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.
Thus, a yield for stock dividends or bond interest paid will be expressed as a percentage of the current price. A yield can also refer to the bond coupon or stock dividend rate divided by the purchase price. There are several specific types of yields. On bonds, a current yield is the annual interest paid divided by the current market price of the bond.