The wavelength of ultrasonic waves is MCQ with Answer and Explanation

The wavelength of ultrasonic waves is
A. Greater than audible sound
B. Same as audible sound
C. Less than audible sound
D. Cannot be determined
Answer: Option C
Solution (By JKExamLibrary)
Velocity v = fλ constant for given medium. Ultrasound has higher frequency (>20 kHz) than audible sound, so wavelength λ = v/f is smaller. Typical ultrasound in MHz range, λ in mm.

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Practice More Physics Questions

Question #1
The temperature of a body is 122°F. In Celsius it is
A. 90°C
B. 50°C
C. 122°C
D. 30°C

Correct Answer: Option B


Explanation:
C = (122-32)×5/9 = 90×5/9 = 50°C.

This question belongs to: Science Physics
Question #2
The frequency of ultrasonic wave is
A. < 20 Hz
B. > 20 kHz
C. 20 Hz - 20 kHz
D. > 20 MHz

Correct Answer: Option B


Explanation:
Above 20 kHz.

This question belongs to: Science Physics
Question #3
In a photoelectric effect experiment, a graph is plotted between the stopping potential (V0) on the y-axis and the frequency of incident light (v) on the x-axis. The slope of this straight line gives the value of:
A. Speed of light (c)
B. Planck's constant (h)
C. Planck's constant divided by electron charge (h/e)
D. Work function of the metal

Correct Answer: Option C


Explanation:
Einstein's photoelectric equation is K_max = hv - W. Since K_max = eV0 (where V0 is stopping potential), eV0 = hv - W. Rearranging for the y-axis variable gives V0 = (h/e)v - (W/e). This is a linear equation y = mx + c. The slope 'm' of the V0 vs v graph is strictly exactly h/e.

This question belongs to: Science Physics