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 = 1.92308Input : 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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