Electromagnetic waves are ripples/oscillations in the invisible electric and magnetic fields that are all around us.

The frequency of a wave is the number of oscillations that occur per second.

The wavelength of a wave is the distance between one point on a wave and the same point on the next wave.

Waves are said to refract when they change direction upon entering a new medium.

An object is opaque if no light is transmitted through it.

Light and colour

Physics

In A-level physics, some pupils will build on this knowledge to learn about the photon model of electromagnetic radiation and the use of electromagnetic radiation for collecting evidence about the universe or for generating images of the inside of a human body.

In the Measuring waves unit, pupils learnt about the measurable features of a wave, the relationship between them and the wave equation.

Electromagnetic waves

oscillations in electric and magnetic fields

Which of the following colours of light has the lowest frequency?

White light is split into its separate colours by this triangular prism. 
This is because some frequencies are {{}} more than others. 

Which of the following statements are true for an opaque blue object?

The light makes the white paper look brown.

The light makes the white paper look yellow.

If pure blue light is also shone onto the paper, the paper will look black.

If pure blue light is also shone onto the paper, the paper will look white.

A student shines pure red light and pure green light onto a white piece of paper. 
Which of the following statements are correct?

Which of the following primary colours of light are transmitted by a cyan filter?

In a {{}} wave, the oscillations are perpendicular (at right angles) to the direction of wave travel.

Most waves happen by oscillations of particles in a substance. 
Which of the following words is used to describe any substance that a wave travels through? 

12 wavelengths pass by a point every hour.

12 wavelengths pass by a point every second.

A sound wave has frequency 12 Hz. 
Which of the following statements explains what a frequency of 12 Hz means?

Which of the following is a correct arrangement of the wave equation?

changes direction if it is travelling perpendicular to the boundary.

changes direction if it is not travelling perpendicular to the boundary.

When a wave crosses a boundary from one medium to another, it …

When a light ray travels from air to glass (and is not moving at right angles to the boundary), the ray bends …

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