76
• Pollution monitoring instrumentation and devices (e.g., optical sensors for heavy
metal detection)
• Health check-up instrumentation
• Using solar energy
Studies on spatial and temporal characteristics of night time light (NTL) before
and during the COVID-19 pandemic in mainland China revealed the monthly average NTL brightness was much lower during the quarantine period than before—due
to lockdown and quarantine policies (Liu et al. 2020).
2.6 Acoustics
Sound is the sense felt by the human ear due to rapid variations in air pressure.
Acoustics was originally restricted to sound, which is created due to pressure waves
in air, which can then be detected by the human ear. Later, the scope of acoustics
was extended to ultrasound and infrasound, which have higher and lower frequencies, respectively, compared to sound.
Noise exposure is linked to disturbance of the homeostasis, annoyance, sleep
disturbance, hypertension, physiological distress, sleep loss, increasing allostatic
Image
f
f
f
f
Fig. 2.21 Line diagram showing the object at 2f
Image
f
f
f
f
Fig. 2.22 Line diagram showing the object beyond 2f
2 Fundamentals of Physics for Environmental and Medical Professionals
• Pollution monitoring instrumentation and devices (e.g., optical sensors for heavy
metal detection)
• Health check-up instrumentation
• Using solar energy
Studies on spatial and temporal characteristics of night time light (NTL) before
and during the COVID-19 pandemic in mainland China revealed the monthly average NTL brightness was much lower during the quarantine period than before—due
to lockdown and quarantine policies (Liu et al. 2020).
2.6 Acoustics
Sound is the sense felt by the human ear due to rapid variations in air pressure.
Acoustics was originally restricted to sound, which is created due to pressure waves
in air, which can then be detected by the human ear. Later, the scope of acoustics
was extended to ultrasound and infrasound, which have higher and lower frequencies, respectively, compared to sound.
Noise exposure is linked to disturbance of the homeostasis, annoyance, sleep
disturbance, hypertension, physiological distress, sleep loss, increasing allostatic
Image
f
f
f
f
Fig. 2.21 Line diagram showing the object at 2f
Image
f
f
f
f
Fig. 2.22 Line diagram showing the object beyond 2f
2 Fundamentals of Physics for Environmental and Medical Professionals