Year 10 Physics – Waves, Optics & EM Revision

Flashcards covering key facts from Year 10 Physics notes on waves, optics, electromagnetic spectrum, lenses, thermal formulas and practical applications.

What equation links wave speed, frequency and wavelength?

v = fλ

Define amplitude of a wave.

The maximum displacement of a particle from its rest (equilibrium) position.

Define wavelength.

The distance travelled by a wave during one complete oscillation (distance between consecutive crests or troughs).

What is a wavefront?

An imaginary line joining all points on a wave that are in phase.

State the main difference between transverse and longitudinal waves.

In transverse waves the vibration is perpendicular to the direction of energy transfer; in longitudinal waves it is parallel.

Which seismic wave is longitudinal?

P-wave (Primary wave).

Which seismic wave is transverse?

S-wave (Secondary wave).

What happens to the speed and frequency of a water wave when it moves from deep to shallow water?

Speed decreases, frequency remains constant.

Which two properties of light change when it enters glass?

Speed and wavelength change; frequency stays the same.

Write the refractive-index formula in terms of incident and refracted angles.

n = sin i / sin r

What is the critical angle?

The incident angle in the denser medium that produces a 90° refracted angle (beyond which total internal reflection occurs).

State Boyle’s law in equation form.

P₁V₁ = P₂V₂ (for a fixed mass of gas at constant temperature).

Give the formula for specific heat capacity.

c = Q / (mΔθ)

Give the formula for specific latent heat.

L = Q / m

What is the speed of any electromagnetic wave in a vacuum?

3.0 × 10⁸ m s⁻¹

Name the EM wave commonly used in satellite communication.

Microwave.

Which EM wave is used in TV remote controls?

Infrared.

Which EM wave helps detect forged banknotes?

Ultraviolet.

Which colour of visible light has the highest wavelength?

Red.

Which colour of visible light has the highest frequency?

Violet.

List two properties common to all electromagnetic waves.

1) They are transverse waves. 2) They obey the wave equation v = fλ (in vacuum v = 3×10⁸ m s⁻¹).

How does a remote control transmit a signal?

By sending pulses of infrared light with patterns unique to each button.

Briefly explain how an infrared burglar alarm works.

Breaking the IR beam between transmitter and receiver triggers a circuit that sounds a buzzer until reset.

Why do bones appear white on an X-ray image?

Dense bone absorbs most X-radiation, preventing it from reaching the detector, so it shows up white.

What lens is used at point P of a magnifying glass setup?

A diverging (concave) lens.

Describe the image produced by a simple magnifying glass.

Virtual, upright, and magnified.

State two changes in a wave when it is refracted.

Its speed and wavelength change; direction also changes if entering at an angle.

If a wave has a frequency of 5 Hz and wavelength 0.8 m, what is its speed?

v = fλ = 5 Hz × 0.8 m = 4 m s⁻¹

Calculate the wavelength of a 76 MHz radio wave in air.

λ = v / f = 3×10⁸ m s⁻¹ / 7.6×10⁷ Hz ≈ 3.95 m

For glass of n = 1.4 and refracted angle r = 32°, find the incident angle i.

i = sin⁻¹ (n sin r) ≈ sin⁻¹ (1.4 × sin 32°) ≈ 47°

State the formula relating power, energy and time.

P = Q / t

Explain dispersion of white light through a prism.

Different wavelengths refract by different amounts, spreading white light into its constituent spectrum of colours.

Why is microwave preferred for satellite links?

It penetrates the atmosphere with low absorption and can carry large bandwidth signals.

What is the effect on wavelength when wave speed decreases but frequency remains constant?

Wavelength decreases proportionally to the speed.

How is heat capacity (C) of an object defined?

The amount of heat required to raise the temperature of the entire object by 1 °C.