You can recall the different expressions for energy of a stationary state, radius and velocity according to Bohr's theory with the sentence:
A student named Ervin goes to a school named Z n Z which has the code 22,2,1.
Easy way to remember the 7 sections of the electromagnetic spectrum!
Photoelectric effect Here's a simple trick to remember the equation of photoelectric effect. Consider a man full of energy, who's planning to displace a ball fixed to the ground with glue. If the man kicks the ball with a force lower than that between the ball and the ground, the ball will not move at all. Let's say he tried again, this time he kicks the ball with a force equal to that between the ball and ground, the ball will unstick from the ground but will not change its position. But if he kicks with more power than before, the ball will gain that extra energy and will be displaced. A man kicking a ball - can be easily compared with what happens in photoelectric effect.