An intensity detector can be moved along a straight track. a source of spherical waves is placed at one end of the track. When the detector is 2 m away from the source, it measures an intensity of 80 W/m2. What distance do we need to move the detector from that position to get a measurement 13 dB lower? Answer: 6.95m

1. (a) What is the intensity in W/m² of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 650 J of energy into a circular spot 1.9 mm in diameter in 4 s? Hint: The laser is a collimated beam of light and does not produce a spherical wave. W/m² (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m²) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is about be very damaging if they enter your eye. ✓times that of the sun, so clearly lasers can

For testing purposes, a musical instrument manufacturing company creates a device so that when you blow into one end with your instrument, sound comes out the other end in opposite directions. A sound technician uses a whistle and generates sound waves with a frequency of 242 Hz. The waves travel in opposite directions in a band room, are reflected by end walls, and return. The band room is 44.0 m long and the whistle is located 14.0 m from one end. What is the phase difference (in degrees) between the reflected waves when they meet at the source of the sound? The speed of sound in air is 343 m/s.

Under favorable conditions, the human eye can detect light waves with intensities as low as 2.50 × 10−12 W/m2. A) At this intensity, what is the average power incident on a pupil of diameter 8.20 mm in W B) If this light is produced by an isotropic source 15.5 m away, what is the average power emitted by the source? in W

An interface is formed between a block of aluminium (with an acoustic impedance of 1.8 x 107 kg m2 s') and a block of copper (with an acoustic impedance of 4.6 x 107 kg m-2 s-1). Longitudinal sound waves travelling through the aluminium are normally incident on the boundary, and are partially reflected. a) What is the ratio of the amplitude of the reflected wave to that of the incident wave? Number b) What is the ratio of the amplitude of the transmitted wave to that of the incident wave? Number c) What percentage of the incident power is transmitted? Number d) What percentage of the incident power is reflected? Number % Ouit P Sove Questi

X A 200 KHz wave travels at 200 m/s. What is its wavelength? * 0.001 m 0.0165 mm 0.01 m 1 m

A 3.49 rad/s (33- rpm) record has a 6.00-kHz tone cut in the groove. If the groove is located 0.100 m from the center of the record (see drawing), what is the "wavelength" in the groove? Number i 58.16 Units m One wavelength 0.100 m

A bat flying at 10.0 m/s is chasing an insect flying in the same direction.  The bat emits a 40.0 kHz chirp and receives back an echo at 40.2 kHz.  How can you tell that the bat will catch the insect without performing any calculations?

Electromagnetic waves can form standing waves. In a standing wave pattern formed from microwaves, the distance between a node and an adjacent antinode is 0.59 cm. What is the microwave frequency?