The relationship between the frequency (f) of an electromagnetic wave, the speed of the wave (which is the speed of light, c) and its wavelength

is given by

Since the wavelength of the radiation in the problem is

, by substituting numbers in the formula we can get the frequency:
The answer is B. On a sunny day, the air over a lake will be cooler than the air over the bordering land.
Batteries supply electrons to the circuit by releasing negatively charged atoms or ions. These ions are produced by the batteries through a chemical reaction that spontaneously occurs within the battery. So the negative end of the battery pushes the ions towards the positive end of the circuit with the help of the voltage. This is why eventually, batteries "run out" when the electrode is used up and the chemical reaction can no longer continue.
Drinking Water - Direct
Our Eating Habits - Direct
Washing Clothes - Indirect