NEET 2020 NEWS
NATIONAL LEVEL OFFLINE TEST
Wave Optics is a section that deals with behaviour of light and its wave characteristics. Wave topics are considered to be easy when it comes to scoring marks in NEET. One can easily score in this topic if prepared thoroughly. To help students prepare Wave Optics for NEET 2020, we are providing students with important topics, revision notes, and some tips and tricks to solve the questions.
We have also added quick notes on each sub topic so that you can quickly cover all the necessary topics. Along with it solved sample questions and previous year exam questions are also given in the article.
According to Huygens Principle, at any instant, the wave front of a wave is defined as the locus of all particles in a medium distributed at the same time and in the same phase of vibration. According to this, each point on a wave front emits its own set of spherical waves (wavelets) and acts as a source of wave fronts. At any point of time, the locus or envelopes of wavelets in the forward direction gives the position of the new wave.
Examples of Huygens Principles:
Question: State for which of the given characteristic dimensions, ray optics is valid?
Question: Find the correct characteristic of the ether medium pervading entire universe according to Hugyen’s principle.
It states that the incidence ray, the reflected ray and the normal to the reflecting surface at the point of incidence all lie on the same plane and that plane is perpendicular to the reflecting surface as shown in the figure below:
Another important sub topic of Physics Wave Optics is Refraction of Light. Refraction of the light is the bending of light when it passes from one source to another. In other words, it is the phenomenon because of which, light when passing from one medium to another changes its velocity. This phenomenon is the reason behind prisms, lenses, rainbows etc. The concept of refraction of light is given in the figure below:
Question: Which of the given lights is least refracted by prism?
Question: For which of the following, the disruptive power will be maximum?
According to the Brewster Law, if an un polarized light is incident at polarizing angle (i) on an interface separating rarer medium from denser medium having refractive index “m”, such that µ = tan i, then reflected light in the rarer medium is completely polarized as shown in the figure below:
Question: Find the polarization angle and angle of refraction respectively if a certain polarizer has a refractive index of 1.33?
The modification obtained due to superposition of two or more waves in the distribution of light energy is called interference.
There are two type of interferences- Constructive Interference and Destructive Interference.
Conditions for constructive Interference:
Conditions for Destructive Interference:
Conditions for Interferences:
Question: What is the ratio of intensities at maxima and minima, if, ratio of amplitude of the two sources producing amplitude is 3:5?
Question: Which of the given concepts id responsible for colors on the soap bubble?
Diffraction refers to bending or spreading of waves when they encounter an object (a barrier) in their path. There are two classes of diffraction-
Question: What is the wavelength of light used if Angular width of central maximum in the Fraunhoffer's diffraction pattern is measured and Slit is illuminated by the light of another wavelength, angular width decreases by 30%.
Question: In comparison with red light how does the diffraction band of blue light look?
Wave Optics is one of the easy topics to score thus making it important when it comes to NEET exam. While Wave Optics in itself is an important topic to prepare for, it also has many important topics which are important from the point of vie of the preparation. Given below is the list of some important sub topics of Wave Optics that needs to prepare with due diligence:
Question: What will be the ratio of resolving power of a Microscope for lights of wavelengths N1= 4000 Å and N2= 6000 Å?
Question: What will be the distance between first dark fringes on either side of the central bright fringe, if, a beam of light of 600 mm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away?
Question: What will be the refractive index of the medium is, if
Question: What will be the ratio at intensity at minima to that at maxima if in a young’s double slit experiment the slit widths are in the ratio of 1:9?
Some tips and tricks to solve NEET 2020 Exams:
On exam day, first go through all the questions in the beginning and then start by solving the easy questions first, then moderate level questions and if time permits then difficult questions. Thus, you will be able to solve more questions in limited time.
Since the date and time of the examination is available, you can start making your schedule according to the day of exam. Start giving mock tests at the same time at which you have exam on the D-Day. This will help your body and mind ready for the exam day.
There will be some questions, where equations will be given as options. Solving these equations and checking each of them consumes a lots of time. Try solving them by putting numbers, this saves your time and narrows down your options too.
Use elimination method to solve the questions. On the exam day, read questions twice and then look at the options carefully. Since it is a MCQ paper, elimination method could be applied in some options and thus will save you a lot of time.
Stay calm and stay focussed and do not panic if you are not able to solve any question. Breathe in, relax and move on to solve next one, and come back to it later on, if you have time.
Since NEET is just around the corner, most of you guys would be done with their syllabus, and would be doing revision these days. So here we provide you with a quick revision plan to help you cover all the necessary topics and some do’s and don’ts to help you within this short span of time: