added resistor divider class.

Author: Mark Hatchell

src/Resistor-Divider.js

@@ -0,0 +1,70 @@
+'use strict';
+
+/**
+ *
+ * ResistorDivider is a class with methods that can be used without initializing.
+ *
+ * It provides the various methods for determining one of the four variables for each calculation.
+ * if (calcVolts)
+ {
+     volts = voltsout*(ohms1+ohms2)/ohms2;
+ }
+ else if (calcOhms1)
+ {
+     ohms1 = volts*ohms2/voltsout-ohms2;
+ }
+ else if (calcOhms2)
+ {
+     ohms2 = voltsout*ohms1/(volts-voltsout);
+ }
+ else if (calcVoltsout)
+ {
+     voltsout = volts*ohms2/(ohms1+ohms2);
+ }
+ * @example
+ *
+ */
+class ResistorDivider {
+
+  /**
+   *
+   * equation is outputVoltage = (inputVoltage * resistor2) / (resistor1 + resistor2)
+   *
+   * @param {number} inputVoltage
+   * @param {number} resistor1
+   * @param {number} resistor2
+   * @returns {{outputVoltage: number}}
+   */
+  static calcOutputVoltage(inputVoltage, resistor1, resistor2) {
+    const outputVoltage = (inputVoltage * resistor2) / (resistor1 + resistor2);
+    return {
+      outputVoltage
+    };
+  }
+
+  static calcResistor2(inputVoltage, outputVoltage, resistor1) {
+    const resistor2 = (outputVoltage * resistor1) / (inputVoltage - outputVoltage);
+    return {
+      resistor2
+    };
+  }
+
+  static calcResistor1(inputVoltage, outputVoltage, resistor2) {
+    const resistor1 = ((inputVoltage * resistor2) / outputVoltage) - resistor2;
+    return {
+      resistor1
+    };
+  }
+
+  static calcInputVoltage(outputVoltage, resistor1, resistor2) {
+    const inputVoltage = ((outputVoltage * (resistor1 + resistor2)) / resistor2);
+    return {
+      inputVoltage
+    };
+  }
+
+}
+
+
+export default ResistorDivider;
+

src/Resistor-Divider.test.js

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+const ResistorDivider = require("./Resistor-Divider");
+
+
+describe('ResistorDivider', () => {
+
+  test('if input voltage is 10 and both resistors are 1000 then output voltage should be 5', () => {
+    expect(ResistorDivider.calcOutputVoltage(10, 1000, 1000)).toEqual({
+      outputVoltage: 5
+    })
+  });
+
+  test('if input voltage is 10, resistor1 is 10000, and resistor2 is 780 then output voltage should be 0.7235621521335807', () => {
+    expect(ResistorDivider.calcOutputVoltage(10, 10000, 780)).toEqual({
+      outputVoltage: 0.7235621521335807
+    })
+  });
+
+  test('if input voltage is 10, resistor1 is 1000, and output voltage is 5 then resistor 2 should be 1000', () => {
+    expect(ResistorDivider.calcResistor2(10, 5, 1000)).toEqual({
+      resistor2: 1000
+    })
+  });
+
+  test('if input voltage is 10, resistor1 is 10000, and output voltage is 0.7235621521335807 then resistor 2 should be 780', () => {
+    expect(ResistorDivider.calcResistor2(10, 0.7235621521335807, 10000)).toEqual({
+      resistor2: 780
+    })
+  });
+
+  test('if input voltage is 10, resistor2 is 1000, and output voltage is 5 then resistor 1 should be 1000', () => {
+    expect(ResistorDivider.calcResistor1(10, 5, 1000)).toEqual({
+      resistor1: 1000
+    })
+  });
+
+  test('if input voltage is 10, resistor2 is 780, and output voltage is 0.7235621521335807 then resistor 1 should be 10000', () => {
+    expect(ResistorDivider.calcResistor1(10, 0.7235621521335807, 780)).toEqual({
+      resistor1: 10000
+    })
+  });
+
+  test('if output voltage is 5 and both resistors are 1000 then input voltage should be 10', () => {
+    expect(ResistorDivider.calcInputVoltage(5, 1000, 1000)).toEqual({
+      inputVoltage: 10
+    })
+  });
+
+  test('if output voltage is 0.7235621521335807, resistor1 is 10000, and resistor2 is 780 then then input voltage should be 9.999999999999998', () => {
+    expect(ResistorDivider.calcInputVoltage(0.7235621521335807, 10000, 780)).toEqual({
+      inputVoltage: 9.999999999999998
+    })
+  });
+
+
+
+
+});