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 :Â
=
+
= here,Â
F is the focal lengthÂ
I is the distance between the lens and the imageÂ
O is the distance between the lens and the object
Examples :Â
Â
Input : O = 50, I = 2
Output : F = 1.92308Input : O = 25, I = 5
Output : F = 4.16667Â
Â
C++
// C++ program to determine // the focal length of a lens #include <iostream> using namespace std;   // Function to determine the focal length of a lens float focal_length(float image_distance, float object_distance) {     return 1 / ((1 / image_distance) + (1 / object_distance)); }   // Driver function int 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 lens def 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 image image_distance = 2  # Variable to store the distance # between the lens and the object object_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 lens using 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. |
PHP
<?php // PHP program to determine // the focal length of a lens // Function to determine the // focal length of a lens function 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 image     $image_distance = 2;       // variable to store the distance     // between the lens and the object     $object_distance = 50;       echo "Focal length of a lens is "        , focal_length($image_distance,                       $object_distance)         , " units .";   // This code is contributed by anuj_67. ?> |
Javascript
<script>   // javascript program to determine // the focal length of a lens   // Function to determine the focal     // length of a lens     function focal_length(image_distance,                               object_distance)     {         return 1 / ((1 / image_distance) +                            (1 / object_distance));     }       // Driver Function            // variable to store the distance         // between the lens and the image         let image_distance = 2;             // variable to store the distance         // between the lens and the object         let object_distance = 50;                     document.write("Focal length of a lens is "        + focal_length(image_distance, object_distance)                                          + " units.");              </script> |
Output
Focal length of a lens is 1.92308 units .
Time Complexity: O(1)
Auxiliary Space: O(1)
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