1. What is the Doppler Effect?

The Doppler Effect is the change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It's commonly experienced with sound waves (like a passing ambulance siren) but also applies to light and other waves.

2. How Does the Calculator Work?

The calculator uses the Doppler Effect equation:

Where:

• \( f \) — Observed frequency (Hz)
• \( f_s \) — Source frequency (Hz)
• \( v_{sound} \) — Speed of sound in medium (m/s)
• \( v_o \) — Observer velocity (m/s)
• \( v_s \) — Source velocity (m/s)

Sign Convention: The signs depend on the relative motion between source and observer.

3. Importance of Doppler Effect

Applications: The Doppler Effect has crucial applications in radar, medical imaging (Doppler ultrasound), astronomy (redshift measurements), and speed detection devices.

4. Using the Calculator

Tips: Enter source frequency, speed of sound (343 m/s in air at 20°C by default), velocities, and select the motion scenario. Positive velocity means motion toward the other object.

5. Frequently Asked Questions (FAQ)

Q1: Why does the pitch change when a vehicle passes by?
A: As the vehicle approaches, sound waves are compressed (higher frequency/pitch). As it moves away, waves are stretched (lower frequency/pitch).

Q2: How does Doppler Effect apply to light?
A: For light, it causes redshift (moving away) or blueshift (moving toward), used in astronomy to measure galaxy movements.

Q3: What's the difference between source moving and observer moving?
A: Mathematically similar but the effect magnitude differs based on which is moving relative to the medium (for sound waves).

Q4: Does wind affect the Doppler shift?
A: Yes, wind effectively changes the speed of sound relative to the ground, affecting the observed frequency.

Q5: How is this used in medical ultrasound?
A: Doppler ultrasound measures blood flow velocity by detecting frequency shifts in reflected ultrasound waves.