Understanding Pin-Hole Cameras

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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?

By generating an 'out of step' wave that interferes destructively with external noise Signup and view all the answers

What is the unit of measurement for pitch?

Hertz (Hz) Signup and view all the answers

What is the relationship between amplitude and loudness?

Higher amplitude corresponds to louder sound, while lower amplitude corresponds to quieter sound Signup and view all the answers

What is the range of human hearing in terms of frequency?

20 Hz to 20,000 Hz Signup and view all the answers

Where in the ear are different frequencies recognised?

In the cochlea, specifically in the 'hair' cells Signup and view all the answers

What is the reason behind the formation of an inverted image in a pin-hole camera?

The light from the top of the object passes through the pinhole and reaches the bottom of the camera screen, and the light from the bottom of the object passes through the pinhole and reaches the top of the screen. Signup and view all the answers

Why does an image become blurry when the pinhole is large in a pin-hole camera?

A large pinhole allows lots of light from one point to enter the box, making it harder to see the image, and it acts like many pinholes overlapping each other. Signup and view all the answers

What is the effect of increasing the distance between the screen and object in a pin-hole camera?

The image becomes bigger and blurrier. Signup and view all the answers

Why is the back of a camera or pin-hole camera typically black?

To absorb light and prevent it from being reflected, which helps to maintain a clear and non-blurry image. Signup and view all the answers

What is the relationship between the angle of incidence and the angle of reflection according to the Law of Reflection?

The angle of incidence is equal to the angle of reflection. Signup and view all the answers

What is the difference between the reflection of light from smooth and rough surfaces?

Reflection from smooth surfaces produces parallel rays, while reflection from rough surfaces produces scattered rays. Signup and view all the answers

What is the term used to describe the scattering of light when it is reflected from rough surfaces?

Diffuse reflection. Signup and view all the answers

What is the orientation of the normal relative to the plane mirror?

The normal is perpendicular to the plane mirror, at an angle of 90 degrees. Signup and view all the answers

What is the characteristic of an image formed by a plane mirror?

The image is laterally inverted, virtual, and the same size as the object. Signup and view all the answers

What happens to the frequency of light when it passes from one medium to another?

It does not change. Signup and view all the answers

What is the relationship between the density of a material and the speed of light?

The more particles in a material, the slower light travels, and the less particles, the faster it travels. Signup and view all the answers

What happens to a ray of light when it passes from a less dense material to a more dense material?

It bends towards the normal. Signup and view all the answers

What is the order of colours in the visible spectrum, and why do they appear in this order?

The order is ROY G BIV, and it appears in this order because red is refracted the least and violet is refracted the most due to their respective wavelengths. Signup and view all the answers

What determines the colour of an object, and how do filters affect the appearance of an object's colour?

The colour of an object is determined by the colours it reflects and absorbs, and filters transmit certain colours and absorb others. Signup and view all the answers

What is the difference between an object appearing white and an object appearing black?

An object appears white if it can reflect all colours on the colour spectrum, and black if it can absorb all colours on the colour spectrum. Signup and view all the answers

What is the purpose of a prism in demonstrating the properties of light?

A prism is used to show how white light disperses into the electromagnetic visible spectrum. Signup and view all the answers

What is the effect on the loudness of sound when the decibel doubles?

The noise is 10 times louder Signup and view all the answers

What is the function of the ossicles in the ear?

To pass on the vibrations from the eardrum to the cochlea Signup and view all the answers

What is the role of the convex lens in the eye?

To refract light and converge light rays to a focus Signup and view all the answers

How does the digital image sensor in a camera convert light waves into an image?

The sensor absorbs the energy from light waves, generating an electrical charge, which is then read by a computer and turned into an image Signup and view all the answers

What is the difference between how light behaves when it hits a mirror versus cardboard?

A mirror has a smooth surface, reflecting light at the same angle, while cardboard has a rough surface, reflecting light in different directions Signup and view all the answers

What is the function of the cochlea in the ear?

To convert vibrations into electric signals Signup and view all the answers

Why do we see an upside-down image on the retina, but not in our brain?

The brain turns the image right-side up Signup and view all the answers

What is the role of the semicircular canals in the ear?

To help with balance Signup and view all the answers

What is the role of the cone in a speaker, and what type of waves does it produce?

The cone vibrates, producing sound waves, which are longitudinal waves. Signup and view all the answers

How do light waves differ from sound waves in terms of their vibration direction?

Light waves are transverse waves, vibrating energy in a direction perpendicular to the wave's travel direction, whereas sound waves are longitudinal waves. Signup and view all the answers

What is the function of a medium in the context of energy transfer?

A medium acts as a carrier, transferring energy (such as sound, light, or heat) from one substance to another, or from one place to another. Signup and view all the answers

Describe how an image is formed in a mirror, including the role of virtual rays.

Rays from the object bounce off the mirror and reflect into the eyes, while virtual rays, which cannot be seen, make the image appear to be behind the mirror. Signup and view all the answers

What is a key similarity between sound and light in terms of their energy and detection?

Both sound and light are forms of energy that can travel from one place to another, and both are detected by our senses (ears for sound, eyes for light). Signup and view all the answers

What is the relationship between the electric signal and the sound waves produced by a speaker?

The electric signal reaches the speaker and causes the cone to vibrate, producing sound waves. Signup and view all the answers

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.