Program for focal length of a lens

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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 <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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