Physics Quiz 1 Quarter 2

Which of the following is an appropriate unit for area?

• Square yards

• Seconds

• Yards

• Inches

Answer explanation

The appropriate unit for area is a square unit, which measures two dimensions. 'Square yards' is correct as it represents area, while 'seconds', 'yards', and 'inches' do not measure area.

What is the reciprocal of 300?

• 30

• .3

• 1/3

• .03

Answer explanation

The reciprocal of a number is 1 divided by that number. For 300, it is 1/300, which equals 0.003 or .03. Thus, the correct answer is .03.

Which of the following best describes waves A and B?

• In phase, will interfere destructively.

• Out of phase, will interfere destructively.

• In phase, will interfere constructively.

• Out of phase, will interfere constructively.

Answer explanation

Waves A and B are out of phase, meaning their peaks and troughs align oppositely. This results in destructive interference, where the waves cancel each other out, leading to a reduction in amplitude.

Which of the following best describes waves B and C?

• Out of phase, will interfere constructively.

• In phase, will interfere destructively.

• In phase, will interfere constructively.

• Out of phase, will interfere destructively.

Answer explanation

Waves B and C are out of phase, meaning their peaks and troughs align oppositely. This results in constructive interference, where the waves combine to form a larger amplitude.

All of the following are acoustic parameters EXCEPT:

• Frequency

• Amplitude

• Wavelength

• Temperature

Answer explanation

Temperature is not an acoustic parameter; it does not describe sound properties. Frequency, amplitude, and wavelength are all key characteristics of sound waves.

Which of the following best describes sound waves?

• Longitudinal, pressure waves

• Transverse, pressure waves

• Longitudinal, out-of-phase waves

• Transverse, Longitudinal waves

Answer explanation

Sound waves are best described as longitudinal, pressure waves because they consist of compressions and rarefactions that travel through a medium, unlike transverse waves which move perpendicular to the direction of energy transfer.

Which of these waves is ultrasonic and most useful in diagnostic sonography?

• 400 mHz

• 200,000 Hz

• 2 kHz

• 4 Mhz

Answer explanation

Ultrasonic waves are above 20 kHz. 200,000 Hz (or 200 kHz) is ultrasonic and commonly used in diagnostic sonography for imaging, making it the correct choice. The other options are either below or not suitable for this purpose.

Using a particular ultrasound system and transducer, which of the following cannot be changed by the operator?

• power

• wavelength

• amplitude

• intensity

Answer explanation

The wavelength of the ultrasound is determined by the transducer and the medium, and cannot be altered by the operator. In contrast, power, amplitude, and intensity can be adjusted during the operation.

What determines the wavelength?

• both the sound source and the medium

• medium

• neither

• sound source

Answer explanation

The wavelength of sound is determined by both the sound source, which affects frequency, and the medium, which influences the speed of sound. Therefore, the correct answer is that both the sound source and the medium determine the wavelength.

How many hertz is 3 MHz?

• 3,000

• .003

• 3,000,000

• 333

Answer explanation

3 MHz (megahertz) equals 3,000,000 hertz because 1 MHz is 1,000,000 Hz. Therefore, 3 MHz = 3 x 1,000,000 Hz = 3,000,000 Hz, making the correct answer 3,000,000.