From the energy that is input into an engine on each cycle, 500 ...

[abarnes]

From the energy that is input into an engine on each cycle, 500 kJ of mechanical work are produced and 600 kJ of heat are exhausted into the environment. What is the efficiency of the engine?
 
  A)
 
  45.5
 
  B)
 
  28.6
 
  C)
 
  90.0
 
  D)
 
  75.0
 
  E)
 
  83.3

Question 2

In a helium-neon laser the emissions occur from transitions between two excited states in neon, one being at 20.66 eV above the ground state and the other being 18.70 eV above ground. What is the energy of the photons emitted by this laser?
 
  A)
 
  20.66 eV
  B)
 
  1.96 eV
  C)
 
  18.70 eV
  D)
 
  19.60 eV
  E)
 
  39.36 eV

[xiaomengxian]

Answer to Question 1

A

Answer to Question 2

B

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Thank you!

[xiaomengxian]

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