P6 Waves Flashcards
What are the two types of waves?
Transverse waves: Oscillations are perpendicular to the direction of energy transfer.
Longitudinal waves: Oscillations are parallel to the direction of energy transfer.
What are examples of transverse and longitudinal waves?
Transverse waves: Ripples on a water surface, electromagnetic waves.
Longitudinal waves: Sound waves in air, seismic P-waves.
What are the features of longitudinal waves?
Compression: Particles are close together.
Rarefaction: Particles are spread out.
What are the key properties of a wave?
Amplitude: Maximum displacement from the rest position.
Wavelength: Distance between the same point on two consecutive waves.
What are frequency and period of a wave?
Frequency: Number of waves passing a point per second (measured in Hertz, Hz).
Period: Time taken for one complete wave to pass a point.
What is wave speed and how is it calculated?
Wave Speed: How fast a wave moves through a medium.
Equation: Wave speed = Frequency × Wavelength.
What are the highest and lowest points of a transverse wave?
Crest: The highest point of a transverse wave.
Trough: The lowest point of a transverse wave.
How can we measure the speed of sound in air? (Required Practical)
Use two microphones a known distance apart.
Clap or produce a sound and record the time taken for the wave to travel between microphones.
Use wave speed = distance / time to calculate speed.
How can we measure the speed of ripples in water? (Required Practical)
Use a ripple tank.
Measure the wavelength with a ruler.
Find frequency using a timer and count waves per second.
Multiply wavelength by frequency to get speed.
What is the law of reflection?
Law of Reflection: Angle of incidence = Angle of reflection.
What is refraction and how does it affect waves?
Refraction: Waves change direction when entering a different medium due to a change in speed.
Denser medium: Slows down and bends towards the normal.
Less dense medium: Speeds up and bends away from the normal.
What is diffraction?
The spreading out of waves when passing through a gap or around an obstacle.
Greater diffraction occurs when the gap is similar in size to the wavelength.
How do we know that waves transfer energy?
Water waves make objects bob up and down without moving them forward.
Sound waves make objects vibrate (e.g., speaker cones).
Electromagnetic waves transfer energy to materials (e.g., heating food in a microwave).
What is the order of the electromagnetic spectrum?
From longest to shortest wavelength:Radio → Microwave → Infrared → Visible Light → Ultraviolet → X-rays → Gamma rays
What is the electromagnetic spectrum?
A continuous range of transverse waves that transfer energy.
All travel at the same speed in a vacuum.
What are the uses of electromagnetic waves? ( radio waves, microwaves and infrared)
Radio waves: TV and radio communication.
Microwaves: Satellite communication, cooking food.
Infrared: Heaters, cooking, night vision cameras.
What are the uses of electromagnetic waves? ( visible light, ultraviolet, x rays, gamma rays)
Visible Light: Fibre optic communication.
Ultraviolet: Fluorescent lamps, sun tanning.
X-rays: Medical imaging.
Gamma rays: Cancer treatment, sterilisation.
How do electromagnetic waves interact with materials? Through absorbtion and transmission
Absorption: Energy is taken in by the material (e.g., infrared on black surfaces).
Transmission: Waves pass through the material (e.g., glass letting visible light through).
Reflection: Waves bounce off a surface (e.g., mirrors reflecting light).
Refraction: Waves change speed and direction when moving between materials.
How do electromagnetic waves interact with materials? Through reflection and refraction
Reflection: Waves bounce off a surface (e.g., mirrors reflecting light).
Refraction: Waves change speed and direction when moving between materials.
What is ionising radiation?
Ionising Radiation: Can remove electrons from atoms, leading to cell damage.
Includes X-rays and gamma rays.
Can cause mutations, cancer, and tissue damage.
What is non-ionising radiation?
Non-Ionising Radiation: Does not remove electrons.
Includes radio, microwave, infrared, visible light, and ultraviolet.
What are the dangers of electromagnetic waves?
Ultraviolet radiation: Causes premature skin aging, skin cancer.
X-rays and gamma rays: Cause mutations, cancer risk.
What safety precautions can be taken against electromagnetic waves?
Lead shielding for X-rays.
Sunscreen for UV protection.
Limiting exposure to radiation sources.
How can we investigate infrared radiation? (Required Practical)
Investigate how different surfaces absorb and emit infrared radiation.
Use a Leslie cube with different surfaces (shiny, matte, black, white).
Measure temperature changes using an infrared detector.
What are the findings from an infrared radiation experiment?
Black, matte surfaces absorb and emit more infrared.
Shiny, white surfaces reflect more infrared and emit less.
