The Diffraction Grating for A Level Physics

-

 

Diffraction grating

Diffraction grating is a glass slide with a series of parallel transparent
lines, called slits, on it.

When a beam of monochromatic beam strikes it, light waves diffract through the slits, creating a pattern of alternating bright and dark spots, known as fringes, on a surface where light falls - in addition to a central, wider bright spot.

At the centre, the light waves meet up in phase. On either side of the central fringe, however, they meet up with with increasing path differences between the waves in question.

 

 


Diffraction grating - wave patterns


For bright fringes, the path differences are multiples of λ and for the dark fringes that alternate between the bright fringes, the path differences are multiples of λ/2.





Comments

Post a Comment

Popular posts from this blog

Phase Difference between Two Points on a Wave and Path Difference Explained - interactive

-
Image
  In the above animation, five points on the wave are considered for the explanation.  The fully interactive applet is given below for you to practise. The phase of a point implies its direction of vibration on a wave. For example, both points A and E vibrate exactly the same way are said to be in phase: when A goes up so does B; the phase difference is either 0 0 or 360 0 . If you consider the motion of points A and C, on the other hand, when A goes down C goes up or vice versa. Therefore, A and C are said to be out of phase; the phase difference is 180 0 . That means the phase difference between two points on a wave - or two waves for that matter - can take any value between 0 0 and 360 0 .  The phase difference between points A and B, for instance, is 90 0 . From the above examples, it is clear there is a connection between the path difference between two points - or two waves - and phase difference. It is as follows: Phase difference = (path difference / wavelength) x 360 φ = x
Read more

Frequency Amplitude and Wavelength of a Transverse Wave - simulation

-
Image
Waves A wave carries energy from a point to another point in a medium / vacuum without the movement of the particles along with it. In the above animation, the wave moves from the left to the right; the particles, however, just vibrate vertically without moving along with the wave. Transverse Waves If the direction of the wave is perpendicular to the vibration of particles, it is called a transverse wave. E.g. Water waves, radio waves, microwaves Amplitude The maximum displacement of a particle in a wave is called amplitude. Intensity / loudness The intensity / loudness of a wave is proportional to the square of the amplitude. The greater the amplitude, the greater the intensity / loudness. Amplifier This is what an amplifier does: it increases the amplitude of an input signal, which in turn leads to the increased loudness or intensity. Frequency  - f The number of cycles of a wave that passes through a point in a unit time is called frequency. Wavelength  - λ The distance between
Read more