A constant frequency signal from a signal generator is fed to two loudspeakers placed $1.5 \mathrm{m}$ apart. A student, who is $8.0 \mathrm{m}$ away from the loudspeakers, walks across in a line parallel to the line between the loudspeakers. The student measures the distance between successive spots of loudness to be $1.2 \mathrm{m}$. Calculate:

(a) The wavelength of the sound

A constant frequency signal from a signal generator is fed to two loudspeakers placed $1.5 \mathrm{m}$ apart. A student, who is $8.0 \mathrm{m}$ away from the loudspeakers, walks across in a line parallel to the line between the loudspeakers. The student measures the distance between successive spots of loudness to be $1.2 \mathrm{m}$. Calculate:

(b) The frequency of the sound (assume the speed of sound is $330 \mathrm{m}{ \mathrm{s}}^{-1}$)

One of the spectral lines from a hydrogen discharge lamp has wavelength $656 \mathrm{nm}$. This light is incident normally at a diffraction grating with $5000$ lines ${\mathrm{cm}}^{-1}$.

Calculate the angles for the first- and second-order maxima for this light

(b) In a double-slit experiment, yellow light of wavelength $590 \mathrm{nm}$ from a sodium discharge tube is used. A student sets up a screen $1.8 \mathrm{m}$ from the double-slit. The distance between $12$ bright fringes is measured to be $16.8 \mathrm{mm}$.

Calculate the separation of the slits.

(c) Describe the effect of:

(i) Using slits of narrower width, but with the same separation

(c) Describe the effect of:

(ii) Using slits with a smaller separation, but of the same width.

(a) A laser light is described as producing light that is both highly coherent and highly monochromatic.

Explain what is meant by the terms coherent and monochromatic.