Physics Chapter 18 important questions with answers

 Physics Chapter 18 – Important Short Questions with Answers

Define Doppler Effect.

Answer: Doppler Effect wo phenomenon hai jisme sound ya light ki frequency source ya observer ke motion ki wajah se change hoti hai.

Applications of Doppler Effect.

Answer:

Radar speed detection

Weather forecasting (rain clouds)

Medical imaging (blood flow measurement)

What is Sound Intensity?

Answer: Sound Intensity ka matlab hai energy per second per unit area jo sound wave transfer karti hai.

Relation between frequency and wavelength.

Answer:

Copy code

v = f × λ

jahan v = speed of sound, f = frequency, λ = wavelength

What is Resonance?

Answer: Resonance wo phenomenon hai jahan system ki natural frequency ke barabar driving frequency apply karne par amplitude maximum ho jata hai.

Examples of resonance.

Answer:

Swing par push karna

Guitar strings ka sound

Glass breaking with high pitch sound

Define Ultrasound.

Answer: Ultrasound sound waves hai jinki frequency > 20,000 Hz hoti hai, jo human ear nahi sun sakti.

Uses of ultrasound.

Answer:

Medical imaging (sonography)

Detecting defects in materials

Cleaning small objects

Explain Echo.

Answer: Echo wo sound hai jo surface se reflect hone ke baad wapas sunai deti hai.

Human ear range of hearing.

Answer: 20 Hz – 20,000 Hz