The Energy Gap Between the Valence and Conduction Bands in a Certain

question 18

Multiple Choice

The energy gap between the valence and conduction bands in a certain semiconductor is 1.25 eV. What is the threshold wavelength for optical absorption in this substance? (c = 3.00 × 10⁸ m/s, 1 eV = 1.60 × 10^-19 J, h = 6.626 × 10^-34 J ∙ s)

• A) 599 nm
• B) 639 nm
• C) 959 nm
• D) 873 nm
• E) 994 nm

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Definitions:

Delusions

False beliefs that are maintained even though they clearly are out of touch with reality.

Hallucinations

Sensory perceptions that occur in the absence of a real external stimulus or that represent gross distortions of perceptual input.

Repression

Keeping distressing thoughts and feelings buried in the unconscious.

Displacement

Diverting emotional feelings (usually anger) from their original source to a substitute target.