The electromagnetic spectrum

An instrumentation laboratory uses four different electromagnetic radiation sources for calibration:

Source P: A microwave transmitter operating at a frequency of $GHz12\text{ GHz}$
Source Q: An infrared laser with a wavelength of $μm1.5\ \mu\text{m}$
Source R: A terahertz sensor operating at a frequency of $THz2.5\text{ THz}$
Source S: A violet LED with a wavelength of $nm405\text{ nm}$

Which of the following correctly lists these sources in order of increasing frequency?

P, R, Q, S

S, Q, R, P

P, S, R, Q

R, P, Q, S

An instrumentation laboratory uses four different electromagnetic radiation sources for calibration:

Source P: A microwave transmitter operating at a frequency of $GHz12\text{ GHz}$
Source Q: An infrared laser with a wavelength of $μm1.5\ \mu\text{m}$
Source R: A terahertz sensor operating at a frequency of $THz2.5\text{ THz}$
Source S: A violet LED with a wavelength of $nm405\text{ nm}$

Which of the following correctly lists these sources in order of increasing frequency?

P, R, Q, S

S, Q, R, P

P, S, R, Q

R, P, Q, S

The electromagnetic spectrum Questions