Yellow-orange light has approximately 3.4 x 10^-19 J of energy. What is its frequency to 1 decimal place?

f = E / h

h = 6.626 x 10^-34

E = 3.4 x 10^-19

A blacklight that makes neon things glow in the dark has a wavelength of about 3.15x10^-7 m. What is its frequency?

$$C=3\times10^8$$

$$\lambda=3.15\ \times\ 10^{-7}$$
$$f\ =\ C\div\lambda$$

A blue light has a wavelength of 4x10^-7 m. What is its frequency, to one decimal place?

$$C=3\times10^8$$

$$\lambda=4\ \times\ 10^{-7}$$
$$f\ =\ C\div\lambda$$

When an electric stove glows red, it is producing near-IR light, of wavelength about 7.9x10^-7 m. What is its frequency to 3 decimal places?

$$C=3\times10^8$$

$$\lambda=7.9\ \times\ 10^{-7}$$
$$f\ =\ C\div\lambda$$

PET scans for medical imaging usually involve a small amount of radioactive decay, producing a gamma ray of the frequency about 1.24x10²⁰ Hz. How much energy does this radiation have?

E = hf

h = 6.626 x 10^-34

f = 1.24x10²⁰