Signup as a Tutor

As a tutor you can connect with more than a million students and grow your network.

CBSE Schools

CBSE Schools

Trending Questions and Lessons

Follow 1,208 Followers

Ask a Question

Feed

All

All

Lessons

Discussion

Lesson Posted on 06 Mar Schools/CBSE Schools CBSE/Class 9/Science Tuition/BSc Tuition/Mathematical Physics +4 CBSE/Class 8/Science/Light Tuition/Class IX-X Tuition Tuition/Class VI-VIII Tuition Tuition/Class VI-VIII Tuition/Science less

Reflection Of Light (Questions)

Soumi Roy

I am an experienced, qualified tutor with over 5 years of experience in teaching maths and physics across...

Reflection of Light Rays on a Reflecting Surface: When a light ray strikes a surface separating two media with different optical properties, part of the light energy is reflected back to the media where it coming from. When light strikes a perfectly reflecting surface, such a mirror for example, all... read more

Reflection of Light Rays on a Reflecting Surface:

When a light ray strikes a surface separating two media with different optical properties, part of the light energy is reflected back to the media where it coming from. When light strikes a perfectly reflecting surface, such a mirror for example, all the light energy is reflected.
We first look at the vocabulary used to describe the reflection of light.

The surface separating the two media is called the interface or boundary.
The point at which the incident ray strikes the interface is called the point of incidence.
i is the angle made by the incident ray and the normal to the interface and is called the angle of incidence.
r is the angle made by the reflected ray and the normal to the interface and is called the angle of reflection.

Laws of reflection:

(1) The incident light ray, the reflected light ray and the normal to the interface at the point of incidence make a plane called the plane of incidence

(2) The angle of incidence and the angle of reflection have the same size.

Example 1: A light ray strikes a reflective plane surface at an angle of 56° with the surface.

a) Find the angle of incidence.

b) Find the angle of reflection.

c) Find the angle made by the reflected ray and the surface.

d) Find the angle made by the incident and reflected rays.

Example 2: A ray of light is reflected by two parallel mirrors (1) and (2) at points A and B. The ray makes an angle of 25° with the axis of the two mirrors.

a) What is the angle of reflection at the point of incidence A?

b) What is the angle of reflection at the point of incidence B?

c) If the distance between the two mirrors id d = 4 cm and the length L of the two mirror system is 3 meters, approximately how many reflections take place between the two mirrors?

d) In a real system, at each reflection, there are losses of the light energy travelling between the two mirrors. If L and d are fixed, what can be done to decrease the number of reflections on the mirrors and hence the energy lost by reflection?

Solution:

a) i = 90 - 25 = 75 °

b) the two mirrors are parallel and AB intersect both of them, hence angle r and i' are alternate interior and therefore equal in size. Also r = i (law of reflection). Hence i' = r = i = 75 °

c) If the distance between the two mirrors id d = 4 cm, AC can be calculated as follows
tan(75°) = AC / d = AC / 4
AC = 4 tan(75°) = 15 cm
The number of reflections N that will take place between the two mirrors may be approximated as follows.
N = L / AC = 3 m / 15 cm = 20

d) Let the angle made by the light ray and the axis of the two mirror system be ? instead of 25 °.
The angle of incidence i = 90 - ? = r = i'
tan(i') = tan( 90 - ?) = cot (?) = AC / d
AC = d cot(?)
number of reflections = N = L / AC = L / d cot(?)
If L and d are fixed, the only way to decrease N is to increase cot(?) and hence decrease ?.

read less
Comments
Dislike Bookmark

Lesson Posted on 11 Jan CBSE/Class 11 CBSE/Class 12 Schools/CBSE Schools

Mathematics: Trigonometric

Amar Singh

I have good experience.

1. ( sinA )2 + (cosA)2 = 1 2. (tanA)2 + (cotA)2 = 1 3. SinA = 1 /cosecA 4. CosA = 1 /secA 5. TanA = 1/cotA (also inverse as secA= 1/ CosA) 6. sin2a = 2 sinA CosA 7. cos2a = (cosa)2 - (sina)2 = 2(cosa)2 - 1 = 1 - 2 (sina)2 8. tan2a = 2tana / 1- (Tana... read more

1. ( sinA )2 + (cosA)2 = 1    

2. (tanA)2 + (cotA)2 = 1   

3. SinA =   1 /cosecA  

4. CosA =  1 /secA

5. TanA = 1/cotA (also inverse as secA= 1/ CosA)

6. sin2a = 2 sinA CosA

7. cos2a = (cosa)2 - (sina)2

               = 2(cosa)2 - 1

               = 1 - 2 (sina)2

8. tan2a =  2tana / 1- (Tana)2.

read less
Comments
Dislike Bookmark

Lesson Posted on 20/11/2017 Schools/CBSE Schools

How to Study Maths: 7 Tips for Solving Maths Problems

Rupam Sasmal

I am an experienced, qualified teacher and tutor with over 10 years of experience in teaching Maths,...

Maths is one of those subjects which you can easily spend hours studying but end up none the wiser. However much you have studied, if you can not solve the problem on day of the test, you are lost. Thankfully, there are some techniques for studying maths that you can do regardless of your level. 7... read more

Maths is one of those subjects which you can easily spend hours studying but end up none the wiser. However much you have studied, if you can not solve the problem on day of the test, you are lost. Thankfully, there are some techniques for studying maths that you can do regardless of your level.

 

7 Tips for Maths Problem Solving:

1. Practice, Practice & More Practice:

It is impossible to study maths properly by just reading and listening. To study maths you have to roll up your sleeves and actually solve some problems. The more you practice answering maths problems, the better. Each problem has its own characteristics and it’s important to have solved it in numerous ways before tackling the exam. There is no escaping this reality, to do well in a Maths exam you need to have solved a LOT of mathematical problems beforehand.

2. Review Errors:

When you’re practising with these problems, it’s important to work through the process for each solution. If you have made any mistakes, you should review them and understand where your problem-solving skills let you down. Understanding how you approached the problem and where you went wrong is a great way of becoming stronger and avoiding the same mistakes in the future.

 

3. Master the Key Concepts:

Do not try to memorise the processes. This is counter-productive. It is much better and rewarding in the long-run to focus on understanding the process and logic that is involved. This will help you understand how you should approach such problems in the future.

Remember that Maths is a sequential subject so it’s important to have a firm understanding of the key concepts that underpin a mathematical topic before moving on to work on other, more complex solutions which are based on understanding the basics.

4. Understand your Doubts:

Sometimes you can get stuck trying to solve part of a maths problem and find it difficult to move on to the next stage. It’s common for many students to skip this question and continue on to the next. You should avoid doing this and instead spend time trying to understand the process of solving the problem. Once you have grasped an understanding of the initial problem, you can use this as a stepping stone to progress to the remainder of the question.

 

5. Create a Distraction Free Study Environment:

Mathematics is a subject that requires more concentration than any other. A proper study environment and a distraction free area could be the determining factor when solving complex equations or problems in geometry, algebra or trigonometry!

Studying with music can help create a relaxing atmosphere and stimulate the flow of information. Having suitable background music can foster an environment of maximum concentration. Of course, you should steer clear of Pitbull and Eminem, instrumental music is the best thing in these times.

6. Create a Mathematical Dictionary:

Mathematics has specific terminology with a lot of vocabulary. We suggest you create Notes or Flashcards with all the concepts, terminology and definitions you need to know. You should include their meanings, some key points and even some sample answers so you can consult them at any time and recap.

7. Apply Maths to Real World Problems:

As much as possible, try to apply real-world problems when approaching maths. Maths can be very abstract sometimes so looking for a practical application can help change your perspective and assimilate ideas differently.

Probability, for example, can be used in everyday life to predict the outcome of something happening and determine whether you want to take a risk such as if you should buy a lottery ticket or gamble.

read less
Comments
Dislike Bookmark

Looking for CBSE Schools

Find best CBSE Schools in your locality on UrbanPro.

FIND NOW

Lesson Posted on 19/09/2017 Schools/CBSE Schools

BlueJ Program For CBSC/ICSE Student

Bishal Saha

I was both student and teacher of computer for a long time.

Consecutive numbers program using array: class Consecutive{public static void main(String[] args){ int a[]={52,10,85,14,32,78,15,11,53,86}; int p=a.length; System.out.println("====Consecutive Numbers Are:===="); for(int i=0;i<p;i++) { for(int j=i+1;j<p;j++) { if((a[i]+1)==a[j]) { System.out.println(a[i]+","+a[j]);... read more

Consecutive numbers program using array:

class Consecutive
{
public static void main(String[] args)
{
int a[]={52,10,85,14,32,78,15,11,53,86};
int p=a.length;
System.out.println("====Consecutive Numbers Are:====");
for(int i=0;i<p;i++)
{
for(int j=i+1;j<p;j++)
{

if((a[i]+1)==a[j])
{
System.out.println(a[i]+","+a[j]);
}
else{
if(a[i]==a[j]+1)
{
System.out.println(a[j]+","+a[i]);
}
}

}
}
}
}

read less
Comments
Dislike Bookmark

Lesson Posted on 19/09/2017 Schools/CBSE Schools

Pattern Slove

Bishal Saha

I was both student and teacher of computer for a long time.

Output: 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 public class Q19c{public static void main(String args[]){int b=5,c=5;for(int i=15; i>=1; i--){System.out.print(i+"\t");if((16-i)==b){System.out.println();c--;b=b+c;}}}} read more

Output:

15  14 13 12 11

10  9   8   7

6    5    4

3    2

1

public class Q19c
{
public static void main(String args[])
{
int b=5,c=5;
for(int i=15; i>=1; i--)
{
System.out.print(i+"\t");
if((16-i)==b)
{
System.out.println();
c--;
b=b+c;
}
}
}
}

read less
Comments
Dislike Bookmark

Lesson Posted on 05/09/2017 Schools/CBSE Schools

6 Tips To Write The Perfect Answer In Cbse Board Exams

Edusmart Skills

EduSmart Skills is an online platform where both the teacher and student come face to face online to...

Appearing for board exams is a tension-ridden phase in the life of the student and parents alike. Best utilization of time and resources is vital to success in the exam. Plan a schedule for completing the portion. Do not leave portions uncompleted till the last month or so. Maintaining good physical... read more
Appearing for board exams is a tension-ridden phase in the life of the student and parents alike. Best utilization of time and resources is vital to success in the exam. Plan a schedule for completing the portion. Do not leave portions uncompleted till the last month or so.
 
Maintaining good physical fitness cannot be overlooked. Keep fit and eat a healthy diet.After all the hard work and preparation, your mind must also be equally prepped to facilitate you to perform your best during the exam. Practice yoga and simple breathing exercises.
 
Tips to answering CBSE board exam questions:
 
  • Read NCERT books and understand the kind of answering pattern that is expected out of you.
  • Carefully go through the sample papers given by the CBSE Board for each subject. This helps you understand the kind of questions as well as the breakup of marks.
  • As every chapter is completed, the student must prepare notes as this will be very useful during revision a day before the exam. On the previous day, it is virtually impossible to go through the entire portion in detail. It is at this time that these notes come handy.
  • Pre-board exams help a student in evaluating their level of preparedness as well as to gauge how they answer the questions. It gives a clue as to the areas of strength and weakness and a student can take corrective action accordingly.
  • Ensure that you have planned your time for each subject paper. Go through the sample question paper and plan out your answering pattern. Some students prefer to answer the papers from the last question. Keep aside a stipulated time for sections based on their weightage.
  • Most importantly it is necessary to maintain cool composure as you take the exam. Do not get agitated if you do not know the answers to a couple of questions. Come back to them after you are done with the ones you know best.
read less
Comments
Dislike Bookmark

Looking for CBSE Schools

Find best CBSE Schools in your locality on UrbanPro.

FIND NOW

Asked on 25/08/2017 Schools/CBSE Schools

My teacher slapped me today just because I got late for class. What should I do now?

Answer

Lesson Posted on 09/08/2017 Schools/CBSE Schools

How To Understand Propositions Better? (For Primary School Students )

BilvaaGuru Learning

Bilvaa Guru Learning is an organization dedicated to making students learn, - covering various areas,...

Propostions are very important in sentence construction. One of the best ways to understand their correct usage is to read books and sentences, and follow the way they have constructed sentences. You should practise constructing similar sentences of your own. For example, start reading an article in... read more

Propostions are very important in sentence construction. One of the best ways to understand their correct usage is to read books and sentences, and follow the way they have constructed sentences. You should practise constructing similar sentences of your own. For example, start reading an article in newspaper a few days back :

  • 'Industrialist arrested for fraud' : Understand how 'for' is used.

  • Use your own experience to create sentences : Ravi was punished by school 'for' coming late.

  • News : ' Viswanathan has to play against Carlsen in the next round'. 'To' is the proposition here.

  • In your explerience : I want to go to Disneyland some time.

  • I have to write the Olympiad exam next month.

  • Of, to, for, with, by, from, till, and such words do a job of linking the subject and the actions or verb. Read many articles for example, newspaper, and try constructing your own sentences.

read less
Comments
Dislike Bookmark

Asked on 31/07/2017 Schools/CBSE Schools

What is the role of government in social and economic development

Answer

Looking for CBSE Schools

Find best CBSE Schools in your locality on UrbanPro.

FIND NOW

Lesson Posted on 18/07/2017 CBSE/Class 4/English/Grammar CBSE/Class 8 CBSE +6 Tuition/Class VI-VIII Tuition/English CBSE/Class 4/English Schools/ICSE Schools Tuition/BA Tuition/English Language Teaching Schools/CBSE Schools Tuition/Class VI-VIII Tuition less

English Language

M.mallick

I graduated from Calcutta University , Dept of Law (hazra campus). I am rewarded with Atul Binod Akhyoy...

Exercise on Modals: (Class 8) Why ________ I care about your problems? (Can/should) Tom and Rebecca give their daughter a lot of presents. They ________ really love her. (can/must) We ________ go out to that new Italian restaurant tonight. (should/must) Everyone who crosses the border ________... read more

Exercise on Modals: (Class 8)

  1. Why ________ I care about your problems? (Can/should)
  2. Tom and Rebecca give their daughter a lot of presents. They ________ really love her. (can/must)
  3. We ________ go out to that new Italian restaurant tonight. (should/must)
  4. Everyone who crosses the border ________ show his/her passport. (must/should)
  5. P1: When is Tom coming? P2: He's on his way. He ________ be here any minute. (must/should)
  6. P1: ________ my friend sleep over? P2: Yes, but he'll have to get permission from his parents. (Can/should)
  7.  ________ you always be so mean to everyone? (can/must)
  8.  ________ you please try to be nicer to your brother? (can/must)
  9. I ________ get here earlier because of the traffic on the freeway. (shouldn’t/ couldn’t)
  10. P1: Which language ________ I learn - French or Italian? P2: I think you ________ learn French. (should/must)
  11. I ____________ be happy to meet Robinson. (a) will b) shall c) Either could be used here).
  12. ________________he play for our team? (a. Will b. Shall c. Either could be used here)
  13. _______________ I get a prize if I stand first in the examination? (a. Will b. Would c. Should)
  14. I _____________be able to beat him. (Express possibility) (a. would b. should c. could)
  15. Watch and pray lest you _____________ fall into temptation. (a. should b. would c. could)
  16. The old man _______________ recline in a corner and sleep most of the time. (Express a habitual action in the past) (a. should b. would c. could)
  17. I ____________ rather read a novel than watch that stupid movie. (a. would b. should c. might)
  18. _______________ you mind lending me your pen for a minute? (a. Should b. Would c. Could)
  19. Till last year, I ______________ read without glasses. (a. would b. should c) could)
  20. If I ____________  fly like a bird, I ______________ be with you now. (a. would, would b. could, would c. could, will d. can, would)

 

read less
Comments
Dislike Bookmark

About UrbanPro

UrbanPro.com helps you to connect with the best CBSE Schools in India. Post Your Requirement today and get connected.

Overview

Lessons 13

Total Shares  

Top Contributors

Connect with Expert Tutors & Institutes for CBSE Schools

x

Ask a Question

Please enter your Question

Please select a Tag