• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month
Page
1. 1
1
2. 2
2
3. 3
3
4. 4
4
5. 5
5
6. 6
6

# Focal length of Concave and Convex lens

Extracts from this document...

Introduction

Focal length of Concave and Convex lens

Objective

In this experiment, we are going to use three different methods and one method to find the focal length of an unknown-focal length of convex lens and concave lens.

## Apparatus

2 meter rules, a light box, a white-coloured screen, a D.C. power supply, 2 lens holders, a plane mirror, a transparent object F, two-unknown focal length of convex and concave lens.

## Theory

Since the convex and concave lenses are made of glasses, the focal lengths are actually the convergent point of all refracted light sources. So, the main theory that we are applying is the refraction theory and also the Lensmaker's equation.

is an equation which shows the relationship between the focal length with the object and image distances. With mathematical simplification, the Lensmaker's equation can be applied as follow .

Procedure

Type A is a convex lens with shorter diameter

Middle

First, put a light source with a transparent object F in front of a convex lens.

Then adjust the distance between the lens and the light source and mark down the distance as D when you can form a sharp image on the screen allocated right beside the light source. The length D is the focal length

METHOD III

By putting the light source in front of the lens and then adjust the distance between the lens and light source and the lens and the screen. Obtain a sharp image and mark down the distance of U and V.

Then plot a graph with U and V to find out the focal length of the lens by applying the equation.

Concave lens

Place the light source in front of the convex lens which is placed between the concave lens and the light source.

Conclusion

Actually, whenever we test the focal length of the lenses we need to consider the degree of the curve of the lens. Since some light rays may refracted near the edge of the lenses and the refracted ray may thus get another focal length and thus resulting a unclear image.

On the other hand the nodal inside the lenses is another interesting topic that students should know. Although we cannot apply the knowledge of it in this experiment, I think most of us should know more about it. It is because this is another factor that affecting the degree of refraction of light rays in lenses.

Lastly, since light ray consist of 7different colours,and what we need to know that the distortion of the rays may happen. So we need to make the total distance of the experiment much smaller.

This student written piece of work is one of many that can be found in our GCSE Waves section.

## Found what you're looking for?

• Start learning 29% faster today
• 150,000+ documents available
• Just £6.99 a month

Not the one? Search for your essay title...
• Join over 1.2 million students every month
• Accelerate your learning by 29%
• Unlimited access from just £6.99 per month

# Related GCSE Waves essays

1. ## Investigation:To find the refractive index of cooking oil.

4 star(s)

Both the results and the graph show that the results were fairly accurate as there is only one anomalous result. Both the ethanol and water results show that the method being used is on the whole; very accurate as the results have been the same as those published.

2. ## Deviation of Light by a Prism.

As you can see from the graph of the Angle of Deviance plotted against the angle of incidence, it is a parabola that achieves a minimum value of 38� when the angle of incidence is 49�. The graph is shaped like it is because, there are in fact two Incident

1. ## SIGNAL ANALYSIS

Compare these values with those off of the graph obtained from the Pico scope. 2. Obtain an Amplitude Modulated (AM) signal. Apply the signal to a spectrum analyser. Explain the measured results. THEORY Filters: The purpose of a filter is to do as the name suggests.

2. ## The aim of my experiment is to see what factors affect electromagnetism the most ...

2nd experiment using the amps as a variable- This also has an increase in its points. The points are in a fairly straight line so the line of best fit will also be straight which means that there is a direct proportionality between the current and the mass of paperclips attracted to the electromagnet.

1. ## Investigating the factors which affect the sideways displacement of a light ray through a ...

from the angle of incidence (i) we will get a direct connection between the result and the sideways displacement. Diagram 2: The results show that as the angle of incidence increases, i -r also increases. This helps us to see that as i increases, the sideways displacement also increases.

2. ## Formulation Of A Theory.

Another reason is that it is an ordinary question used in most surveys and questionnaires in similar subjects. The steps that will be taken to avoid bias are to note down the people's estimations straight away with the truth being considered in order to avoid changing answers so that the hypothesis is right from the start.

1. ## Is there any rule governing the angle light is refracted through?

You work out angle r if you have the refractive index number of the substance you are working with and the angle of incidence. To work this out you would need the following equation: R= sin sin i N = Refractive Index n Prediction: I predict that when the light enters the Perspex block (which is optically more dense)

2. ## Sideways Displacement of a Light Ray

* experiment should be done on straight horizontal surface, so that any parts of the equipment will not go over the edge (e.g. of the table, where the experiment is carried out) * I must be careful with the equipment, because : * the glass is easy to break or

• Over 160,000 pieces
of student written work
• Annotated by
experienced teachers
• Ideas and feedback to