What is a wave? How is a wave created - A wave transfers energy from one place to another without any overall transfer of matter. In order to make a wave something needs to vibrate, What is a transverse wave?  - In a transverse wave vibrations are at right angles (perpendicular) to the direction of energy transfer (direction of the wave). , What waves are tranverse - Waves on the surface of water (ripples) and light are two examples of transverse waves, What is a longitudinal wave? - In a longitudinal wave vibrations are in the same direction (parallel) as the direction of energy transfer (direction of the wave), What waves are longitudinal? - Sound is an example of a longitudinal wave, What is the definition of frequency? What is its unit? - The frequency of a wave is defined as the number of vibrations per second (or the number of waves per second). Its unit is Hz (Hertz), What is the definition of time period? - Time period is defined as the time for one vibration (or the time for one wave to pass a point)., What is the definition of amplitude? - The definition of amplitude is the maximum distance of a vibrating particle from its rest position., What is the definition of wavelength? - The definition of wavelength is the distance from a point on a wave to the same point on the next wave., How is a sound wave produced? - A sound wave is produced when something vibrates., What do sound waves do? - Sound waves (or sound radiation) transfer energy from the source of the sound (vibrating object) to our ears., What happens to the particles in a substance when a sound wave passes through them? - Particles vibrate in a direction that is parallel to the direction of the wave. Sometimes particles are close together (compressions) and sometimes they are far apart (rarefaction), Why can’t sound waves travel through a vacuum? - A vacuum is a place where there are no particles at all. Space is a vacuum. Sound waves cannot travel through a vacuum because particles need to vibrate in order for the energy transfer to take place., How can you demonstrate that sound waves can’t travel through a vacuum? - You can demonstrate that sound waves can’t travel through a vacuum by putting a bell (or any source of sound) into a strong glass jar that is connected to a vacuum pump. As the air particles are removed from the jar by the pump the bell gets quieter. When all of the air particles have been removed the bell will be in a vacuum and is no longer heard, How does a sound wave change when sounds are louder or higher in pitch? - When a sound is made louder the amplitude of the wave increases. When a sound is a higher pitch the frequency of vibrations increases and time period decreases., What is the range of human hearing? - 20Hz to 20,000Hz (20kHz), What are sounds higher that 20kHz known as? What are they used for? - Sounds with a higher pitch than 20kHz are known as ultrasound. Ultrasound can be used in medical imaging, medical treatments, and distance measurements and in industry., How can you measure the speed of sound? - Someone stood 100m away (measured with a tape measure) makes a visible sound (e.g. by banging two blocks of wood together) and someone at the other end starts a stop clock when they see the sound being made and stops the stop clock when they hear it. Speed = distance / time. A more accurate way would be to use microphones and electronic timers because this removes all human reaction time.,

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