An electron microscope achieves much higher resolution than a light microscope because
Correct answer: B. the de Broglie wavelength of a fast electron is far shorter than the wavelength of visible light
- A. electrons travel faster than light
- B. the de Broglie wavelength of a fast electron is far shorter than the wavelength of visible light
- C. electrons are smaller than photons
- D. it uses a stronger lens
Explanation
Resolution is limited by wavelength, and accelerating electrons to high speed gives them a wavelength of the order of a picometre, thousands of times shorter than visible light. Magnetic lenses then focus them in place of glass. Electrons certainly do not travel faster than light, which rules out the first option immediately.
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About Photons and the Particle Model of Light
The particle model treats light as photons with energy E equals hf and momentum related to wavelength. Questions involve the photoelectric effect, work function, threshold frequency, stopping potential and photon energy, while distinguishing particle behaviour from the wave description of interference and diffraction.
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