A Level Physics Practice Exam

How is energy transmitted in a sound wave?

1. By particles being static

2. By particles moving sideways only

3. By particles vibrating and causing compressions and rarefactions

4. By a solid medium only

The correct answer is: By particles vibrating and causing compressions and rarefactions

Energy in a sound wave is transmitted through the vibration of particles in the medium, which leads to the formation of compressions and rarefactions. In a medium such as air, water, or solids, sound waves propagate as mechanical waves where the particles oscillate around their equilibrium positions. This oscillation creates regions of high pressure (compressions) where particles are closer together and regions of low pressure (rarefactions) where they are farther apart. As particles vibrate, they transfer kinetic energy to adjacent particles, causing them to also vibrate and continue the energy transfer throughout the medium. This mechanism is essential for sound wave propagation; without the vibrations and the resultant pressure changes, sound could not travel through the medium. In contrast, other options overlook this fundamental aspect of sound wave transmission. For instance, if particles were static, there would be no movement to transmit energy, and if they only moved sideways, the longitudinal nature of sound waves wouldn't be realized. Additionally, sound can travel through various media, not just solids; it requires a medium but does not have to be exclusively solid.