What resistance R3 in parallel with resistances R1=10K Ω and R2=20K Ω gives an
equivalent resistance of Req=50 Ω

Answer:

A C program typically consists of a number of components, including preprocessor directives, function prototypes, global variables, functions, and a main function.

Explanation:

Here's an explanation of each component, followed by an example C program that demonstrates their usage:

Preprocessor Directives: Preprocessor directives are instructions to the C preprocessor, which processes the source code before compilation. They usually start with a '#' symbol. Some common directives are #include for including header files and #define for defining constants.

Function Prototypes: Function prototypes provide a declaration of functions that will be used in the program. They specify the function's name, return type, and the types of its parameters.

Global Variables: Global variables are variables that can be accessed by any function in the program. They are usually defined outside of any function.

Functions: Functions are blocks of code that can be called by name to perform specific tasks. They can accept input parameters and return a value. Functions are generally declared before the main function.

Main Function: The main function is the entry point of the program. It's where the execution starts and ends. It has a return type of int and typically takes command-line arguments via two parameters: argc (argument count) and argv (argument vector).

Here's an example C program that demonstrates the structure:

// Preprocessor directives

#include <stdio.h>

// Function prototypes

void print_hello_world(void);

// Global variable

int global_var = 10;

// Functions

void print_hello_world(void) {

   printf("Hello, World!\n");

}

// Main function

int main(int argc, char *argv[]) {

   // Local variable

   int local_var = 20;

   printf("Global variable value: %d\n", global_var);

   printf("Local variable value: %d\n", local_var);

   print_hello_world();

   return 0;

}

This simple C program demonstrates the use of preprocessor directives, a function prototype, a global variable, a function, and the main function. When run, it prints the values of a global and a local variable, followed by "Hello, World!".