At every instant the ratio of the magnitude of the electric to the magnetic field in an electromagnetic wave in vacuum is equal to
a. the speed of radio waves.
b. the speed of light.
c. the speed of gamma rays.
d. all of the above. e. only (a) and (b) above.
D
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A major process in modifying Earth's crust is erosion by wind
a. True b. False Indicate whether the statement is true or false
Exhibit 17-3Four wave functions are given below. I.y(x, t) = 5sin(4x- 20t + 4) II.y(x, t) = 5sin(3x- 12t + 5) III.y(x, t) = 5cos(4x + 24t + 6) IV.y(x, t) = 14cos(2x- 8t + 3)Use this exhibit to answer the following question(s). Refer to Exhibit 17-3. Rank the wave functions in order of the magnitude of the frequencies of the waves, from least to greatest.
A. IV, II, I, III B. IV = II, I, III C. III, I, II, IV D. IV, I, II, III E. III, IV, II, I
If the plane x = 4 m is an equipotential surface, in which of the following directions can the electric field be in the region immediately adjacent to this plane?
a. the positive y direction b. both the positive and negative z directions c. the positive x direction d. more than one of these choices
The focal lengths of the objective and the eyepiece in a microscope are 0.29 cm and 2.50 cm, respectively. An object is placed at 0
30 cm from the objective lens and the image of this object is viewed with the eyepiece adjusted for minimum eyestrain (with the eye focused at the far point). The near point of the person using the microscope is 25 cm and the far point is at infinity. What is the final overall magnification of the microscope? A) -320 x B) -470 x C) -240 x D) -300 x E) -190 x