Sound

This course is a part of Class 9 Physics (India), a 3-course Topic series from Khan Academy.

There are sounds all around us. But the clap of your hand sounds very different from that of a flute. Why? How sound is produced? How do we hear it? Why do we sometimes hear echoes? Are there sounds that we can't hear? In this chapter, we will explore these and many more such questions.

This course contains 5 segments:

Production, propagation & properties of sound

When you clap your hands or play music, you hear a sound. But what is sound? And how sound is produced? That's the topic of this lesson.

Longitudinal waves & speed of sound

Let's talk about the speed of sound. In this lesson, we will derive a relationship between speed, wavelength, and frequency of a wave. We will also explore the meaning of longitudinal waves.

Reflections, echoes, and reverberation

You may have heard echoes when in the mountains, whereas you may have heard annoying reverberations in empty halls. You would have seen doctors use stethoscopes to hear your heartbeat. All these things have one thing in common, reflection of sound. In this lesson, we will explore the reflection of sound.

Ultrasound

You may have heard of ultrasound. But what is it? Why is it used? Let's explore it in this lesson

Structure of human ear

Our ears help us hear and differentiate millions of different tones. But how do they work? What's inside our ears? That's exactly what we will explore in this lesson.