2013
11-09

# Bode Plot

Consider the AC circuit below. We will assume that the circuit is in steady-state. Thus, the voltage at nodes 1 and 2 are given by v1 = VS coswt and v2 = VRcos (wt + q ) where VS is the voltage of the source, w is the frequency (in radians per second), and t is time. VR is the magnitude of the voltage drop across the resistor, and q is its phase.

You are to write a program to determine VR for different values of w. You will need two laws of electricity to solve this problem. The first is Ohm’s Law, which states v2 = iR where i is the current in the circuit, oriented clockwise. The second is i = C d/dt (v1-v2) which relates the current to the voltage on either side of the capacitor. “d/dt”indicates the derivative with respect to t.

The input will consist of one or more lines. The first line contains three real numbers and a non-negative integer. The real numbers are VS, R, and C, in that order. The integer, n, is the number of test cases. The following n lines of the input will have one real number per line. Each of these numbers is the angular frequency, w.

For each angular frequency in the input you are to output its corresponding VR on a single line. Each VR value output should be rounded to three digits after the decimal point.

1.0 1.0 1.0 9
0.01
0.031623
0.1
0.31623
1.0
3.1623
10.0
31.623
100.0

0.010
0.032
0.100
0.302
0.707
0.953
0.995
1.000
1.000

import java.util.Scanner;

public class Main {

static double vs = 0;
static double c = 0;
static double r = 0;
static double w = 0;
static int times = 0;

public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
vs = scan.nextDouble();
r = scan.nextDouble();
double r2 = r * r;
double vsr = vs * r;
c = scan.nextDouble();
double c2 = c * c;
times = scan.nextInt();
for (int i = 0; i < times; i++) {
w = scan.nextDouble();
System.out.printf("%.3f\n", vsr / Math.sqrt(r2 + 1 / (w * w * c2)));
}
}
}

1. #include <cstdio>

int main() {