Energy of a photon : E = hf The photoelectric effect works like this. If you shine light of high enough energy on to a metal, electrons will be emitted from the metal. Light below a certain threshold frequency, no matter how intense, will not cause any electrons to be emitted.
The Boogie Board Jot 8.5 is an uber-slim slate with a black 8.5â³ screen. The stylus clicks into the opening under the screen. When you use the stylus it writes on the screen in a bright green color. The company claims this board is 50% brighter than their previous Jot model.
Model: YOUTEK Graphene Speed Pro. Head size: 100 sq in. String pattern: 18x20. Four of the current Top 10 men's singles players use a variation of the Head Youtek racket, including none other than second-ranked Novak Djokovic. While each racket in the series is exceptional in its own regard, Djokovic's Youtek Graphene Speed Pro is a great option for players looking to take their game to the next level.