What is the equation for depth?

What is the equation for depth?

• A. Depth (mm) = go-return time (µs) / 1.54
• B. Depth (mm) = 1.54 mm/µs × go-return time (µs) / 2
• C. Depth (mm) = 2 × go-return time (µs) ÷ 1.54
• D. Depth (mm) = go-return time (µs) × 1.00 / 2

Answer: (B)

Depth is found from how far the ultrasound travels on its round trip. Since the go-return time covers both the outward and return paths, you multiply that time by the speed of sound in the medium to get the total distance traveled, and then divide by two to get the one-way depth to the reflector. Using the given reference speed of 1.54 mm/µs, the depth works out to go-return time × 1.54 ÷ 2. If a different material were involved, you’d plug in that material’s speed of sound instead. The other forms either omit the division by 2, invert the relationship, or use an incorrect velocity value, leading to the wrong depth.

Depth is found from how far the ultrasound travels on its round trip. Since the go-return time covers both the outward and return paths, you multiply that time by the speed of sound in the medium to get the total distance traveled, and then divide by two to get the one-way depth to the reflector. Using the given reference speed of 1.54 mm/µs, the depth works out to go-return time × 1.54 ÷ 2. If a different material were involved, you’d plug in that material’s speed of sound instead. The other forms either omit the division by 2, invert the relationship, or use an incorrect velocity value, leading to the wrong depth.