Course

O Level Physics: Waves, Light and Sound (5054)

Name: O Level Physics: Waves, Light and Sound (5054)
Price: 1499 BDT

The whole of 5054 section 3, taught step by step: waves, reflection and refraction, lenses and ray diagrams, the electromagnetic spectrum and sound, with worked examples, practice and exam questions in every chapter.

70 lessons12h 12mEnglish

What you'll learn

Say what a wave transfers and what it leaves behind, and use v = f lambda in either direction
Describe reflection, refraction and diffraction of waves, and what a ripple tank shows
Use the law of reflection and describe the image in a plane mirror
Calculate with n = sin i / sin r and n = 1 / sin c, and explain how an optical fibre keeps light in
Draw ray diagrams for a converging lens and describe the image as real or virtual, upright or inverted, enlarged or diminished
Put the electromagnetic regions in order both ways, and give uses and dangers for each
Explain pitch and loudness, and work an echo or sonar calculation without losing the return journey

Requirements

Speed as distance divided by time, from 5054 section 1.2, kinematics
The particle model of solids, liquids and gases, from 5054 section 2.1: sound needs it and light does not
Sine of an angle in degrees, and finding an angle back from its sine on a calculator
Rearranging a two-term equation such as v = f lambda for any one of its symbols
Standard form, so that 3.0 x 10^8 m/s and a 500 nm wavelength can be compared
Converting between metres, centimetres and millimetres inside one calculation

Course content

70 lessons · 12h 12m

3.1 · General properties of waves

What a wave carries, transverse and longitudinal waves, amplitude, wavelength, frequency and v = fλ, then reflection, refraction and diffraction in the ripple tank.

0/15

Waves transfer energy without transferring matter

A ball on the pond bobs up and down but never reaches the shore: the wave carries energy, not water.

Preview10m 2.

Transverse waves

The rope moves up and down while the wave runs along it: vibration at 90° to the travel.

Preview11m

Longitudinal waves

Push and pull a slinky: the coils vibrate along the travel, making compressions and rarefactions.

11m

Describing a wave: crest, trough, amplitude and wavelength

Amplitude is measured from the middle, not from the bottom. Sea waves 3.0 m high have amplitude 1.5 m.

12m

Frequency, wavefronts and wave speed

Frequency is waves per second, the period is seconds per wave, and a wavefront joins one crest.

12m

The wave equation

Two waves of 2.0 m leave Leo’s hand each second, so the wave moves 4 m each second: v = fλ.

12m

Using the wave equation

Turn v = fλ round for λ or f, and change MHz, kHz, cm and mm first. 100 MHz radio waves are 3.0 m long.

12m

The ripple tank

Crests focus the lamp into bright lines. Measure across many lines and divide by the gaps.

11m

Reflection of waves at a plane surface

Angle in equals angle out, both measured from the normal. Only the direction changes.

11m

10.

Refraction of waves

Shallow water slows the waves, so they bunch up and turn towards the normal. The frequency never changes.

12m

11.

Diffraction through a gap

A gap about one wavelength wide spreads the wave out most. That is why sound gets through a doorway and round the side.

12m

12.

Diffraction at an edge

Longer waves bend further round an edge: the drum is heard round the corner, the cymbal much less.

11m

13.

General properties of waves: practice

A timed drill of mixed questions: types of wave, amplitude, frequency, v = fλ and what waves do.

14.

General properties of waves: exam practice

Exam-style questions on the ripple tank, earthquake waves and a harbour, with mark schemes and worked solutions.

15m

15.

General properties of waves: summary

The key points, the wave equation and the common mistakes on one screen, with cards to revise from.

3.2.1-3.2.2 · Reflection and refraction of light

The law of reflection and the image in a plane mirror, then refraction, refractive index, the critical angle, total internal reflection and optical fibres.

0/14

Reflection of light: the normal, angle of incidence and angle of reflection

Every angle is measured from the normal, a line at 90° to the mirror. A beam 30° from the glass has i = 60°.

Preview10m 2.

The law of reflection

The angle of incidence always equals the angle of reflection, so the rays are 2i apart.

Preview11m

The image in a plane mirror

Same size, same distance behind the glass, and virtual: 2.0 m in front means 4.0 m from your image.

11m

Constructions and calculations with plane mirrors

Find an image by drawing, build a periscope, and see why a mirror turned 10° turns the beam 20°.

12m

Refraction of light: the angle of refraction

Light slows in water and glass and bends towards the normal; coming out, it bends away. That bends the straw.

12m

Refraction by transparent blocks

Trace a ray through a glass block with crosses and a protractor. It comes out parallel to how it went in.

14m

Refractive index and the speed of light

Refractive index is speed in air ÷ speed in the material. Glass, n = 1.5, slows light to 2.0 × 10⁸ m/s.

12m

Calculating refractive index: n = sin i / sin r

Divide the sines, not the angles: i = 40° and r = 25° give n = 1.52.

13m

Critical angle and total internal reflection

Past about 42° inside glass, no light gets out: all of it reflects back. That is total internal reflection.

13m

10.

Calculating the critical angle: n = 1 / sin c

sin c = 1 ÷ n, then sin⁻¹. Glass gives 41.8°, water 48.8° and diamond 24.4°.

12m

11.

Optical fibres

Light bounces along a glass thread by total internal reflection, carrying phone calls, TV and the internet.

13m

12.

Reflection and refraction of light: practice

A timed drill of mixed questions, then a bonus mission to carry a signal through mirrors, glass and fibre.

13.

Reflection and refraction of light: exam practice

Exam-style questions on a glass block, a mirror wall and a fibre link, with mark schemes and worked solutions.

15m

14.

Reflection and refraction of light: summary

The laws, the three refractive-index equations and the common mistakes on one screen, with cards to revise from.

3.2.3-3.2.4 · Thin lenses and dispersion of light

Converging and diverging lenses, ray diagrams for real and virtual images, the magnifying glass and glasses for short and long sight, then dispersion and the colours of the spectrum.

0/12

Converging and diverging lenses

A lens that is fat in the middle brings parallel rays to one point; one that is thin in the middle spreads them out.

Preview10m 2.

Focal length, principal axis and principal focus

Focus a distant window on a card: the distance from lens to card is the focal length.

Preview12m

Ray diagrams for a real image

Two of three rules find any image: parallel then through F, straight through the centre, through F then parallel.

13m

Describing an image

Real or virtual, upright or inverted, bigger or smaller: where the object sits decides all three.

12m

Virtual images

Inside the focal length the rays never meet, so trace them backwards: the image is virtual and upright.

12m

The magnifying glass

Hold the label inside the focal length and look through: a 4 mm letter looks 8 mm tall and upright.

11m

Correcting short-sightedness and long-sightedness

Short sight focuses in front of the retina and needs a diverging lens; long sight needs a converging one.

11m

Dispersion of light

Glass bends violet a little more than red, so a prism fans white light into a spectrum.

11m

The visible spectrum and monochromatic light

Red, orange, yellow, green, blue, indigo, violet: frequency rises, wavelength falls. A laser has just one frequency.

11m

10.

Thin lenses and dispersion: practice

A timed drill on lenses, images, glasses and colour, then a bonus mission with one lens.

11.

Thin lenses and dispersion: exam practice

Exam-style questions on a ray diagram, the concert projector and colours, with mark schemes and worked solutions.

15m

12.

Thin lenses and dispersion: summary

The rays, the object-position table, glasses and the spectrum on one screen, with cards to revise from.

3.3 · Electromagnetic spectrum

The seven regions in order, their shared speed of 3.0 × 10⁸ m/s, what each is used for and the harm it can do, how signals reach us, and analogue against digital.

0/11

The regions of the electromagnetic spectrum

Radio, microwave, infrared, visible, ultraviolet, X-ray, gamma: frequency up, wavelength down.

Preview11m 2.

The speed of electromagnetic waves

Every EM wave travels at 3.0 × 10⁸ m/s in a vacuum, so Wi-Fi at 2.4 GHz is 0.125 m long.

Preview12m

Uses of radio waves and microwaves

Radio for broadcasting, astronomy and RFID; microwaves for satellite TV, phones and ovens.

11m

Uses of infrared, visible light and ultraviolet

Infrared toasts and switches channels, visible light lets us see, and ultraviolet makes hidden ticket marks glow.

11m

Uses of X-rays and gamma rays

X-rays pass through muscle but not bone; gamma rays sterilise sealed equipment and treat cancer.

11m

Harmful effects of electromagnetic radiation

Heating at the long end, damage to cells at the short end: sunscreen for UV, a lead apron for X-rays.

12m

Communication using electromagnetic waves

Microwaves to satellites and phones, radio waves for Bluetooth, light and infrared down the fibre.

12m

Analogue and digital signals

A digital signal has only 1s and 0s, so noise can be stripped out and the signal rebuilt perfectly.

12m

Electromagnetic spectrum: practice

A timed drill on the order, the speed, the uses, the dangers and the signals.

10.

Electromagnetic spectrum: exam practice

Exam-style questions on the regions, a satellite link and the afternoon sun, with mark schemes.

15m

11.

Electromagnetic spectrum: summary

The order, the uses, the dangers and the signals on one screen, with cards to revise from.

3.4 · Sound

How vibrations make sound, why it needs a medium, what we can hear, loudness and pitch, the speed of sound and how to measure it, echoes, and ultrasound at sea and in hospitals.

0/13

The production of sound by vibrating sources

Touch a speaker and feel it buzz: every sound starts with something vibrating.

Preview10m 2.

Sound as a longitudinal wave: compressions and rarefactions

The air is squeezed and stretched along the direction the sound travels; compression to compression is one wavelength.

Preview11m

Sound needs a medium

Pump the air out of the jar and the bell goes quiet, though you can still see it ringing.

11m

The range of human hearing

People hear from about 20 Hz to 20 000 Hz, and the top end falls with age. A dog hears higher.

10m

Loudness and pitch

Taller waves are louder, closer waves are higher. Read both from a screen trace.

13m

The speed of sound in solids, liquids and gases

About 340 m/s in air, faster in water, fastest in steel. Count after the lightning to find the storm.

11m

Measuring the speed of sound in air

Time the bang from 500 m away, starting on the flash. Repeat and average: about 340 m/s.

13m

Echoes

An echo is reflected sound. It goes there and back, so halve the distance.

11m

Ultrasound

Sound above 20 kHz: too high to hear, with a wavelength short enough to show fine detail.

10m

10.

Uses of ultrasound: sonar, medical scanning and testing materials

Send a pulse, time the echo, halve: the depth of the sea, a baby scan or a hidden crack.

12m

11.

Sound: practice

A timed drill on sound, then a bonus mission to repair a sound link from speaker to listener.

12.

Sound: exam practice

Exam-style questions on an echo, measuring the speed of sound and a fishing boat, with mark schemes.

15m

13.

Sound: summary

The facts, the echo rule and the common mistakes on one screen, with cards to revise from.

About the creator

8bitlesson

Cambridge O Level, A Level and university courses, taught through interactive labs.

Mentora builds the sciences and mathematics as things you can move rather than videos you watch. Cambridge O Level and A Level mathematics, physics, chemistry and accounting, a primary mathematics track, and first-year university computer science. Every lesson works a real exam question end to end.