To produce beats it is necessary to use two waves: 

A. traveling in opposite directions 

B. of slightly different frequencies 

C. of equal wavelengths 

D. of equal amplitudes 

E. whose ratio of frequencies is an integer

Consider two imaginary spherical surfaces with different radii, each centered on a point sound source emitting spherical waves. The power transmitted across the larger sphere is the power transmitted across the smaller and the intensity at a point on the larger sphere is the intensity at a point on the smaller. 

A. greater than, the same as 

B. greater than, greater than 

C. greater than, less than 

D. the same as, less than 

E. the same as, the same as

A long string is constructed by joining the ends of two shorter strings. The tension in the strings is the same but string I has 4 times the linear mass density of string II. When a sinusoidal wave passes from string I to string II: 

A. the frequency decreases by a factor of 4 

B. the frequency decreases by a factor of 2 

C. the wave speed decreases by a factor of 4 

D. the wave speed decreases by a factor of 2 

E. the wave speed increases by a factor of 2

Amount by which one oscillation leads or lags behind another is called

A. in phase

B. intensity

C. phase difference

D. superposition

Speed of electromagnetic radiation is independent of 

A. wavelength 

B. amplitude 

C. time period 

D. frequency

Electric and magnetic fields vary at angle of

A. 30°

B. 90°

C. 45°

D. 180°

Phase difference is measured in

A. degrees

B. meters

C. seconds

D. newton

Take the speed of sound to be 340 m/s. A thunder clap is heard about 3 s after the lightning is seen. The source of both light and sound is: 

A. moving overhead faster than the speed of sound 

B. emitting a much higher frequency than is heard 

C. emitting a much lower frequency than is heard 

D. about 1000 m away 

E. much more than 1000 m away

Intensity of a wave is directly proportional to the

A. amplitude

B. square of amplitude

C. cube of amplitude

D. frequency

Two identical strings, A and B, have nearly the same tension. When they both vibrate in their fundamental resonant modes, there is a beat frequency of 3 Hz. When string B is tightened slightly, to increase the tension, the beat frequency becomes 6 Hz. This means: 

A. that before tightening A had a higher frequency than B, but after tightening, B has a higher frequency than A 

B. that before tightening B had a higher frequency than A, but after tightening, A has a higher frequency than B 

C. that before and after tightening A has a higher frequency than B 

D. that before and after tightening B has a higher frequency than A 

E. none of the above