IB MYP 4-5 Physics- Wave imaging and real-life applications- Study Notes - New Syllabus
IB MYP 4-5 Physics-Wave imaging and real-life applications- Study Notes
Key Concepts
- Wave imaging and real-life applications
Wave Imaging
Wave Imaging
Wave imaging refers to the use of waves (mechanical or electromagnetic) to form pictures or gather information about objects, surfaces, or structures. Different types of waves are used in different imaging technologies.
Sound Waves (Ultrasound Imaging)
High-frequency sound waves are sent into the body. The echoes reflected back are detected and converted into images (used in medical ultrasound to view organs, blood flow, or a fetus in pregnancy).
Electromagnetic Waves
- X-rays – High-frequency electromagnetic waves penetrate soft tissue but are absorbed by bone, producing shadow images of bones and dense objects.
- Infrared Imaging – Detects heat radiation emitted by objects, often used in night vision cameras and thermal scanners.
- Microwaves (Radar) – Used in radar systems to detect the position and speed of aircraft, ships, and even rainfall clouds.
- Radio Waves (MRI) – In Magnetic Resonance Imaging (MRI), radio waves combined with strong magnetic fields create detailed images of soft tissues in the body.
Real-life Applications of Wave Imaging
Medical Applications
Ultrasound scans, X-ray radiography, MRI scans, CT scans – used for diagnosis and monitoring health conditions.
Industrial Applications
Ultrasonic testing to detect cracks in metal parts, X-ray imaging to check product quality, and radar to monitor aircraft or ships.
Environmental Applications
Satellite imaging with infrared and microwave waves to study weather patterns, pollution, and natural disasters.
Security Applications
X-ray scanners at airports, infrared cameras for surveillance at night, and sonar (sound imaging) for submarine navigation.
Key Idea
Different wave types are selected based on their wavelength, frequency, and ability to penetrate materials. Shorter wavelengths (like X-rays, gamma rays) give high detail but can be harmful, while longer wavelengths (radio, microwave) are safer but give lower resolution.
Example:
An ultrasound machine sends a pulse of sound into the body at a speed of \( v = 1540 \,\text{m/s} \) (in soft tissue). The echo returns after \( 0.00026 \,\text{s} \). Calculate the depth of the tissue boundary where the echo was reflected.
▶️ Answer/Explanation
Step 1: Distance traveled by ultrasound = speed × time.
\( d_\text{total} = v \times t = 1540 \times 0.00026 = 0.4004 \,\text{m} \)
Step 2: The sound travels to the tissue and back, so the actual depth is half of this distance.
\( d = \dfrac{0.4004}{2} = 0.200 \,\text{m} \)
Final Answer: The boundary is at a depth of \(\boxed{0.200 \,\text{m}}\).
Example:
An X-ray has a frequency of \( 3.0 \times 10^{18} \,\text{Hz} \). Calculate its wavelength in meters. (Speed of electromagnetic waves \( c = 3.0 \times 10^{8} \,\text{m/s} \)).
▶️ Answer/Explanation
Step 1: Use the wave equation: \( v = f \lambda \).
Here, \( c = f \lambda \).
Step 2: Solve for wavelength:
\( \lambda = \dfrac{c}{f} = \dfrac{3.0 \times 10^{8}}{3.0 \times 10^{18}} \)
\( \lambda = 1.0 \times 10^{-10} \,\text{m} \)
Final Answer: The X-ray wavelength is \(\boxed{1.0 \times 10^{-10} \,\text{m}}\).
Example:
A radar system sends a microwave pulse towards an airplane. The pulse returns after \( 0.00024 \,\text{s} \). If the speed of microwaves is \( 3.0 \times 10^{8} \,\text{m/s} \), calculate the distance of the airplane.
▶️ Answer/Explanation
Step 1: Total distance traveled by the pulse:
\( d_\text{total} = c \times t = 3.0 \times 10^{8} \times 0.00024 \)
\( d_\text{total} = 7.2 \times 10^{4} \,\text{m} \)
Step 2: Actual distance to airplane is half of this (since the wave travels to the plane and back).
\( d = \dfrac{7.2 \times 10^{4}}{2} = 3.6 \times 10^{4} \,\text{m} \)
Final Answer: The airplane is at a distance of \(\boxed{36 \,\text{km}}\).