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Multiple-choice quiz

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Simulation of a transverse wave

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The wavelength of any wave is the distance between two matching points on neighbouring waves.

Wavelength of a transverse wave

The wavelength is the same whichever two matching points are used to measure this distance.

wavelength

wavelength

wavelength

The symbol used to represent wavelength is .

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The amplitude of any wave is the maximum distance a point moves from its rest position.

Amplitude of a transverse wave

The amplitude of a transverse wave is the height of a peak or trough from the wave’s rest position of the wave.

amplitude

amplitude

The larger the amplitude, greater the energy of the wave.

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Investigating transverse waves

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Frequency of waves – activity

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Simulation of a longitudinal wave

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Transverse or longitudinal waves?

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Total internal reflection – simulation

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Optical fibres are thin strands of solid glass, about the size of a human hair.

What are optical fibres?

They are widely used in communication, medicine, lighting and as sensors.

The first transatlantic telephone cable to use optical fibres went into operation in 1988.

Optical fibres can transmit light signals at high speed over long distances and are used in phone and internet connections.

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Why are optical fibres so important?

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Optical fibres do not have to be straight to carry light and can even carry light around corners.

How do optical fibres carry light?

Light travels through the Perspex rod, and optical fibres, by aprocess called total internal reflection.

This curved Perspex rod shows how light travels in an optical fibre.

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What is total internal reflection?

A ray of light enters the optical fibre.

light enters optical fibre

light leaves optical fibre

As the light enters the optical fibre, it is refracted. This means that the direction the light is travelling in changes.

The ray of light hits the wall of the fibre and is totally internally reflected when the angle of incidence is greater than the critical angle.

The ray of light passes down the optical fibre by repeated total internal reflection.

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What’s in a cable of optical fibres?

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Optical fibres can be used by doctors to look inside a patient’s body without having to cut them open to check that they are healthy.

The device used for this purpose is called an endoscope. It contains a bundle of optical fibres that are held together and can be inserted into the body.

How are optical fibres used in medicine?

Light is sent down some of the fibres and the image is reflected back through the other fibres.

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Optical fibres – true or false?

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Multiple-choice quiz