GUIDE QUESTIONS The size of the minima and maxima increases as the slit width decreases, and vice ve rsa. Moreover, the number of minima and maxima increases when the slit width increases and vice versa. The theory in diffraction is consistent and correct; the theory tells us that slit is divided into 2 elements and that light from this area element strike the same point on the screen and it is divided into equal elements. If light is incident onto an obstacle which contains two ve ry small slits a distance d apart, the n the wavelets emanating from each slit will constructively interfere behind the obstacle.When light passes through a single slit whose width w is o n the order of the wavelength of the light, then we observe a single slit diffraction pattern. Huygen's principle tells us that each part of the slit can be thought of as an emitter of waves. All these waves interfere interfere to produce the diffraction pattern. pattern. The principal difference between an interference pattern caused by two slits and that caused by a grating is that a grating has more intense bright fringes that are more widely-spaced. These two effects should make sense. The brightness would increase since more light can reach the screen (there are more openings, or slits, in the barrier). The greater spacing can be accounted for by the fact that since d is getting increasingly smaller, y would get increasing larger. ANALYSIS Diffraction is a property of the motion of all waves which is a phenomenon by which a wave encounters a barrier or an obstacle. Interference is phenomenon by which two or more waves tend to overlap, thus, interfere with one another. When waves interfere with each other, the t he amplitude of the resulting wave depends on the frequencies, relative phases (relative positions of the crests and troughs), and amplitudes of the interfering waves. The first part of the experiment measures the wave length of a single slit disk. Part II of the experiment measures the wavelength using two slit interference. Just like in the first part of the experiment, the light should be diffracted. Having the measured values, wavelength is now computable. By gett ing the wavelength at different position we attained its average and this value should conform in the accepted value of the wavelength. On both parts, diffraction is observed when the light rays tend to bend from a much smaller barrier or passageway to be projected on the screen with an image having a larger magnitude than the width of the slit. Interference of light waves is observed on the se cond part of the experiment when the light rays pass on two different slits and interfere with the wave of the other which is observed on the screen as much smaller divisions of bright and dark fringes. The slit may be divided into equal area elements with each are element acting as a source of o f secondary waves. These wave patterns are the one which could be observed by us in the screen. We had observed that the measurement of minima and maxima increases as the slit decreases. CONCLUSION I therefore conclude that the distance of every minima and maxima are equal to each other. The measurement of the minima and maxima increases as the slit decreases. The measurement of the
minima and maxima decreases as the distance of the screen to the slit decreases. We must also consider several factor in performing the expe riment, we must know what kind of color t he laser produces in able to know the wavelength of that spec ific color because every color have different wavelength. In real life application, for diffraction, if a radio is tur ned on in one room, the sound from t he radio can be heard in an adjacent room even from around a doorway. Similarly, whenever water waves pass an object on the surface of the water, such as a jetty or boat dock, waves that pass the object's edge spread out into the region behind the object and directly blocked by it. An example of interference also radio waves which interfere with each ot her when they bounce off buildings in cities, distorting radio signals. Sound-wave interference must be taken into account when constructing concert halls, so that destructive interference does not r esult in areas in the hall where the sounds produced on stage cannot be heard. 1.
When light of wavelength , L , is incident on a slit of width, a , then a screen placed a distance, R , from the slit will show a diffraction pattern with the location, y , of the first dark fringe (measured from the central bright fringe) of; y = RL/a
2.
This is an approximation which is quite good for , R >> a >> L Diffraction is the result of superposition of light waves from same wave train. so it is observed in single slit. In Double slit we observe interference of light.Here frigewidth = wavelength*screen distance/screen separation as frigewidth increases when screen separation decreases so gradually position of bright frige shifted away.
Increase the slit separation and the fringes get closer together. Increase the distance to the screen and the fringes get further apart.
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