Waves and the particle nature of light

A sound wave has frequency 250 Hz and wavelength 1.36 m. What is its speed?

Polarisation shows that light is:

Light in air hits water (n = 1.33) at an angle of incidence of 40°. Calculate the angle of refraction and the critical angle for water.

A grating has 600 lines per mm. Calculate the angle of the second-order maximum for light of wavelength 589 nm.

Electrons accelerated through 150 V pass through a thin graphite film. Calculate their de Broglie wavelength and explain why a diffraction pattern is seen.

An ultrasound pulse (speed 1540 m s⁻¹ in tissue) returns from a boundary after 65 μs. Calculate the depth of the boundary and explain why high frequencies give better resolution.

Light of intensity 800 W m⁻² falls on a 1.6 m² solar panel that is 20% efficient. Calculate the electrical power output and the number of photons hitting the panel each second, assuming all have wavelength 550 nm.

Explain why polarising sunglasses reduce glare from a wet road.

Describe how to measure the speed of sound in air using a signal generator, loudspeaker, two microphones and an oscilloscope.

At 2.0 kHz the microphone was moved 0.86 m while the traces came back into phase five times. Calculate the speed of sound.

Describe how to determine the wavelength of laser light using a diffraction grating.

A grating with 300 lines per mm is 1.50 m from a screen. The two second-order maxima are 1.20 m apart. Calculate the wavelength.