3.3.2.2 Diffraction

Question 1

What is observed in the single slit diffraction pattern using monochromatic light

Answer 1

A central bright fringe that is wider and more intense than the outer fringes which are narrower and decrease in intensity

Question 2

What is observed in the single slit diffraction pattern using white light

Answer 2

A central white fringe with coloured fringes on either side caused by different wavelengths diffracting by different amounts

Question 3

How does increasing the wavelength affect the central diffraction maximum

Answer 3

Makes the central maximum wider because diffraction increases with wavelength

Question 4

How does increasing slit width affect the central diffraction maximum

Answer 4

Makes the central maximum narrower because diffraction decreases as slit width increases

Question 5

What is a plane transmission diffraction grating

Answer 5

A flat plate with a very large number of equally spaced parallel slits

Question 6

What happens when monochromatic light passes through a diffraction grating

Answer 6

Light is diffracted at specific angles to produce bright maxima due to constructive interference

Question 7

What is the diffraction grating equation

Answer 7

d sin theta equals n lambda

Question 8

In the diffraction grating equation what does d represent

Answer 8

Separation between adjacent slits on the grating

Question 9

In the diffraction grating equation what does theta represent

Answer 9

Angle of diffraction of the nth order maximum from the central maximum

Question 10

In the diffraction grating equation what does n represent

Answer 10

The order number of the diffraction maximum

Question 11

In the diffraction grating equation what does lambda represent

Answer 11

Wavelength of the light

Question 12

What is required for a diffraction maximum to occur

Answer 12

Path difference between rays must equal a whole number of wavelengths for constructive interference

Question 13

What is an application of diffraction gratings

Answer 13

Measuring wavelengths of light accurately in a spectrometer

Question 14

Why are diffraction gratings useful in spectroscopy

Answer 14

Because they produce sharp bright lines at specific angles for precise wavelength measurement

Question 15

What happens to the diffraction pattern when white light passes through a diffraction grating

Answer 15

Each wavelength is diffracted at a different angle producing a continuous spectrum of colours at each order