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Questions and Answers
What are the primary colours in science?
Red, green, and blue
What is the result of combining green and blue light?
Cyan
What is the mechanism by which sound waves are detected in the ear?
Vibrations in the eardrum and cochlea
How do noise-cancelling headphones work?
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What is the unit of measurement for pitch?
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What is the relationship between amplitude and loudness?
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What is the range of human hearing in terms of frequency?
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Where in the ear are different frequencies recognised?
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What is the reason behind the formation of an inverted image in a pin-hole camera?
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Why does an image become blurry when the pinhole is large in a pin-hole camera?
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What is the effect of increasing the distance between the screen and object in a pin-hole camera?
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Why is the back of a camera or pin-hole camera typically black?
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What is the relationship between the angle of incidence and the angle of reflection according to the Law of Reflection?
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What is the difference between the reflection of light from smooth and rough surfaces?
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What is the term used to describe the scattering of light when it is reflected from rough surfaces?
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What is the orientation of the normal relative to the plane mirror?
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What is the characteristic of an image formed by a plane mirror?
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What happens to the frequency of light when it passes from one medium to another?
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What is the relationship between the density of a material and the speed of light?
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What happens to a ray of light when it passes from a less dense material to a more dense material?
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What is the order of colours in the visible spectrum, and why do they appear in this order?
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What determines the colour of an object, and how do filters affect the appearance of an object's colour?
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What is the difference between an object appearing white and an object appearing black?
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What is the purpose of a prism in demonstrating the properties of light?
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What is the effect on the loudness of sound when the decibel doubles?
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What is the function of the ossicles in the ear?
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What is the role of the convex lens in the eye?
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How does the digital image sensor in a camera convert light waves into an image?
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What is the difference between how light behaves when it hits a mirror versus cardboard?
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What is the function of the cochlea in the ear?
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Why do we see an upside-down image on the retina, but not in our brain?
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What is the role of the semicircular canals in the ear?
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What is the role of the cone in a speaker, and what type of waves does it produce?
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How do light waves differ from sound waves in terms of their vibration direction?
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What is the function of a medium in the context of energy transfer?
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Describe how an image is formed in a mirror, including the role of virtual rays.
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What is a key similarity between sound and light in terms of their energy and detection?
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What is the relationship between the electric signal and the sound waves produced by a speaker?
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Study Notes
Colours
- The primary colours are red, green, and blue.
- Red + Green = Yellow
- Green + Blue = Cyan
- Blue + Red = Magenta
Sound
- Sound is created by vibrations, which travel through the air as waves.
- Sound travels faster in solids because the particles are closer together, making vibration transmission easier.
- Higher frequency means the sound waves are more squashed together, while higher amplitude means the sound waves have a larger height.
- Lower frequency means the sound waves spread apart, while lower amplitude means the sound waves have a smaller height.
- The greater the amplitude of sound, the louder it is.
- The smaller the amplitude of sound, the quieter it is.
- The smaller the frequency of a sound, the lower its pitch.
- Human audible frequency range: 20 Hz to 20,000 Hz.
Noise Cancelling Headphones
- Noise cancelling headphones work by generating an 'out of step' wave that interferes destructively with external noise, cancelling it out.
Pin-hole Cameras
- Light travels in a straight line, so the image is inverted in a pin-hole camera.
- The smaller the pinhole, the sharper the image.
- Increasing the distance between the screen and object results in a blurrier image.
- Reducing the distance between the screen and object results in a sharper image.
Reflection
- Reflection occurs when light travelling through one material bounces off a different material.
- The Law of Reflection states that the angle of incidence equals the angle of reflection.
- Smooth surfaces produce parallel rays, allowing us to see the image, while rough surfaces scatter rays, producing diffuse reflection.
Plane Mirrors
- Images on plane mirrors are laterally inverted and cannot touch the screen, making them virtual.
- The image 'behind' the mirror is the same size and distance from it.
Refraction
- Light changes speed as it passes from one medium to another.
- The frequency of light does not change as it refracts.
- The refractive index of a material measures the change in light speed as it passes from a vacuum into the material.
Light Dispersion
- White light disperses into its constituent colours when passing through a prism.
- Different colour wavelengths are refracted by different amounts.
- Red is refracted the least, and violet is refracted the most.
- ROY G.BIV is a mnemonic for remembering the colours of the visible spectrum.
Colour Filters
- Coloured filters transmit some colours and absorb all others.
- Objects appear white if they reflect all colours, and black if they absorb all colours.
- Coloured objects reflect some colours and absorb others.
Ear Anatomy
- The pinna collects sound vibrations, which are funnelled through the ear canal to the eardrum.
- The eardrum vibrates, and these vibrations are passed on to the ossicles, and then to the cochlea.
- The cochlea converts the vibrations into electrical signals, which are transmitted to the brain through the nerve.
- The semicircular canals help with balance.
How We See
- The retina is the part of the eye where images are formed.
- The convex lens refracts light, causing the light rays to converge and focus.
- The lens can change shape to focus light from objects at different distances.
Digital Image Sensors
- Digital image sensors absorb the energy carried by light waves from the image.
- The energy from the light waves causes the sensor to generate an electrical charge.
- The changes in electrical charge are read by a computer and turned into an image.
Mirrors
- Smooth surfaces, like mirrors, reflect light rays at the same angle, producing a clear reflection.
- Rough surfaces, like cardboard, scatter light rays, making it impossible to see a reflection.
Sound Waves
- Electric signals cause sound waves when they reach a speaker, making the cone vibrate.
- Longitudinal waves, like sound waves, vibrate in the same direction as the wave.
- Light waves are transverse waves, vibrating perpendicularly to the wave direction.
Medium
- A medium is a material that transfers energy, like light or sound, from one substance to another.
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Description
Learn how pin-hole cameras work, including how light enters the hole, gets focused, and projects an inverted image on the opposite side of the box.