Program for focal length of a lens

• Last Updated : 12 Apr, 2021

Write a program to determine the focal length of a lens.
Focal length is the distance between the center of the lens to the principal foci. In order to determine the focal length of a lens we should know the distance between the lens and the image ( I ) and the distance between the lens and the object ( O ). Here, we will use the lens equation also called the focal length equation.
The lens equation is : = + here,
F is the focal length
I is the distance between the lens and the image
O is the distance between the lens and the object
Examples :

Input : O = 50, I = 2
Output : F = 1.92308

Input : O = 25, I = 5
Output : F = 4.16667

C++

 // C++ program to determine// the focal length of a lens#include using namespace std; // Function to determine the focal length of a lensfloat focal_length(float image_distance, float object_distance){    return 1 / ((1 / image_distance) + (1 / object_distance));} // Driver functionint main(){    // variable to store the distance    // between the lens and the image    float image_distance = 2;     // variable to store the distance    // between the lens and the object    float object_distance = 50;     cout << "Focal length of a lens is "         << focal_length(image_distance, object_distance)         << " units .";     return 0;}

Java

 // Java program to determine// the focal length of a lens import java.io.*; class GFG {     // Function to determine the focal    // length of a lens    static float focal_length(float image_distance,                              float object_distance)    {        return 1 / ((1 / image_distance) +                           (1 / object_distance));    }     public static void main(String[] args)    {         // variable to store the distance        // between the lens and the image        float image_distance = 2;         // variable to store the distance        // between the lens and the object        float object_distance = 50;                 System.out.println("Focal length of a lens is "        + focal_length(image_distance, object_distance)                                         + " units.");    }} // This code is contributed by Ajit.

Python3

 # Python3 program to determine# the focal length of a lens # Function to determine the focal length of a lensdef focal_length(image_distance, object_distance)    : return 1 / ((1 / image_distance) + (1 / object_distance)) # Driver Code# Variable to store the distance# between the lens and the imageimage_distance = 2 # Variable to store the distance# between the lens and the objectobject_distance = 50 result = focal_length(image_distance, object_distance)print("Focal length of a lens is ", result, " units.")

C#

 // C# program to determine// the focal length of a lensusing System; class GFG {     // Function to determine the focal    // length of a lens    static float focal_length(float image_distance,                            float object_distance)    {        return 1 / ((1 / image_distance) +                    (1 / object_distance));    }         // Driver code    public static void Main()    {         // variable to store the distance        // between the lens and the image        float image_distance = 2;         // variable to store the distance        // between the lens and the object        float object_distance = 50;                 Console.WriteLine("Focal length of a lens is "        + focal_length(image_distance, object_distance)                                        + " units.");    }} // This code is contributed by Vt_m.



Javascript



Output :

Focal length of a lens is 1.92308 units .

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