MCAT Physical : Other Light Principles

Study concepts, example questions & explanations for MCAT Physical

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Example Questions

Example Question #1 : Other Light Principles

Which of  the following is/are ionizing radiation?

  1. microwaves
  2. X-rays
  3. gamma rays
  4. all of the above
  5. 2 and 3, but not 1
Possible Answers:






Correct answer:



Choice 5 is correct.  Highly energetic frequencies such as X-rays and gamma rays can displace electrons from materials upon which they impinge.  Microwaves are a form of radio waves, which are long-wavelength, low frequency waves with little energy. 

Mnemonic:  Microwave ovens are fundamentally safe household items.

Example Question #2 : Other Light Principles

An incandescent light bulb is shown through a glass prism. The certain wavlength of the light is then directed into a glass cuvette containing an unknown concentration of protein. Commonly, this process is called spectroscopy and is used to determine the concentrations of DNA, RNA, and proteins in solutions. The indices of reflection of air, glass, and the solution are 1, 1.5, and 1.3, respectively.

Light is a __________

Possible Answers:

particle or wave, depending on wavelength

particle and a wave



Correct answer:

particle and a wave


As Einstein determined, light has properties of both a particle and a wave. In the particle sense, it has mass, velocity, and momentum. The wave property of light allows for diffraction, and constructive and destructive interference. For the MCAT, it is important to know that the photon (the particle of light) has both particle and wave properties. In fact, all objects have both particle and wave properties; however, their wave property becomes less obvious with increasing mass.

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