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) 959 nm B) 873 nm C) 994 nm D) 599 nm E) 639 nm
C
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One of the advantages of charge-coupled devices over photographic plates is that a CCD can record bright and faint objects on the same exposure
a. True b. False Indicate whether the statement is true or false
Rotational Kinetic Energy: A hoop is rolling without slipping along a horizontal surface with a forward speed of 5.50 m/s when it starts up a ramp that makes an angle of 25.0° with the horizontal. What is the speed of the hoop after it has rolled 3.00 m up as measured along the surface of the ramp?
A. 4.22 m/s B. 1.91 m/s C. 2.06 m/s D. 3.79 m/s E. 8.02 m/s
Faraday's Law: A closed flat loop conductor with radius 2.0 m is located in a changing uniform magnetic field. If the emf induced in the loop is 2.0 V, what is the rate at which the magnetic field strength is changing if the magnetic field is oriented perpendicular to the plane in which the loop lies?
A. 0.16 T/s B. 1.0 T/s C. 0.080 T/s D. 2.0 T/s
Every heat engine
A) gains heat from a high-temperature reservoir. B) converts energy into mechanical work. C) expels heat to a lower-temperature reservoir. D) all of the above E) none of the above