Light in a frozen block of ice reflects off the ice-air interface and undergoes a phase shift of
A) 0.
B) 45.
C) 90.
D) 180.
E) 270.
Question 2
Compared to a chemical rocket, an ion engine has a
A) smaller thrust but can be operated for a longer time period
B) smaller thrust and can only be operated for a shorter time period
C) larger thrust and can be operated for a longer time period
D) larger thrust but can only be operated for a shorter time period