10th Class Physics Chapter 2 Notes Urdu Medium

Complete Notes on Chapter No.11:  10th Class Physics Chapter 2 Notes Urdu Medium in 10th Class Physics Urdu Medium written by Professor Sir Fahad Abbas Suib. These computerized notes are very helpful in the preparation of 10th Class Physics Chapter 2 Notes Urdu Medium for students of the 10th class Physics and these are according to the paper patterns of all Punjab boards.

• Sound is a form of energy that can be heard and travels in waves.
• When matter vibrates or moves back and forth very quickly a sound is made.
• Sound waves can travel through solids liquids or gases
• For example, when a school bell rings parts of the bell will vibrate creating sound.
• Sound is a type of energy made by vibrations. When any object vibrates, it causes Movement in the air particles. These particles jump into the particles close to them. This movement is called sound waves. The picture is stored and thrown into a still body of water. The rigs of waves expand indefinitely. When the vibrations are fast, you hear a high note. When the vibrations are slow, it creates a slow note. OR
• Sound waves travel through the air at a certain speed called the speed of sound. This is evident from natural observation. A flash of lightning is seen in the distance, and after a while thunder is heard. The speed of sound depends on pressure, temperature, density, and their combination. Suppose, a sound wave travels through a stagnant gas. A sound wave produced by a source, say a firecracker in the corner of a room. If you are standing in the middle of the room, the sound wave travels past you at some speed. The sound wave itself is a thin region of disturbance in the air, with slightly changing pressure, temperature, and density. The change in pressure is what stimulates your eardrum and allows you to hear the sound wave.
• SOUND WAVES: Like other waves, sound is also produced by vibrating bodies. Due to vibrations of bodies the air around them also vibrates and the air vibrations produce sensation of sound in our ear. For example, in a guitar, sound is produced due to the vibrations of its strings. Our voice results from the vibrations of our vocal chords. Human heart beats and vibrations of other organs like lungs also produce sound waves. Doctors use stethoscope to hear this sound.
• In school laboratories, we use a device called tuning fork to produce a particular sound. If we strike the tuning fork against rubber hammer, the tuning fork will begin to vibrate. We can hear the sound produced by tuning fork by bringing it near our ear. We can also feel the vibrations by slightly touching one of the prongs of the vibrating tuning fork with a plastic ball suspended from a thread.
• Explain how sound is produced by vibrating sources and that sound waves require a material medium for their propagation.
• Describe the longitudinal nature of sound waves (as a series of compressions and rarefactions).
• Define the terms pitch, loudness and quality of sound.
• Describe the effect of change in amplitude on loudness and the effect of change in frequency on pitch of sound.
• Define intensity and state its SI unit.
• Describe what is meant by intensity level and give its unit.
• Explain that noise is a nuisance.
• Describe how reflection of sound may produce echo.
• Describe audible frequency range.
• Describe the importance of acoustic protection.
• Solve problems based on mathematical relations learnt in this unit.
• Describe that some sounds are injurious to health.
• Describe how knowledge of the properties of sound waves is applied in the design of building with respect to acoustics.
• Describe how ultrasound techniques are used in medical and industry.
• Explain the use of soft materials to reduce echo sounding in classroom studies, and other public gathering buildings.
• We know that vibrations of objects in any medium produce waves. For example, vibrator of ripple tank produces water waves. The medium in this case is liquid, but it can also be a gas or a solid. Now we will discuss another type of waves that we can hear i.e., sound waves.