Learn Git: Remote Location 2/8

git clone science-quizzes my-quizzes

Codecademy: Sample Solution to "Using Objects" under the jQuery Track

//First, the object creator
function makeGamePlayer(name,totalScore,gamesPlayed) {
    //should return an object with three keys:
    // name
    // totalScore
    // gamesPlayed
    gamePlayerObject = {
    "name" : name,
    "totalScore" : totalScore,
    "gamesPlayed" : gamesPlayed
};
    return gamePlayerObject;
}

//Now the object modifier
function addGameToPlayer(player,score) {
    //should increment gamesPlayed by one
    //and add score to totalScore
    //of the gamePlayer object passed in as player
    player.gamesPlayed++;
    player.totalScore = player.totalScore + score;
}

Question: How is maximum power transfer attained in AC circuits?


Answer:

Maximum power transfer occurs when the impedance Z is purely resistive. This is achieved by utilizing capacitors for power factor correction.

Question: What are the powers normally associated with AC circuits?


Answer:

The types of powers normally associated with AC circuits are real power and reactive power.

Question: The total power dissipation in an RL series circuit is due to which component?


Answer:

The total power dissipation is due to the resistance.

Question: How does frequency affect the impedance and admittance of a capacitor?


Answer:

The impedance Z of a capacitor is given as 1/jwC where w is 2(π)f. The higher the frequency, the smaller the value of the impedance.

Admittance Y is simply the reciprocal of impedance. Therefore the higher the frequency, the larger the value of the admittance.

Question: How does frequency affect the impedance and admittance of an inductor?


Answer:

The impedance Z of an inductor is given as jwL where w is 2(π)f. The higher the frequency, the larger the value of the impedance.

Admittance Y is simply the reciprocal of impedance. Therefore the higher the frequency, the smaller the value of the admittance.

Question: What is the voltage waveform produced by an AC generator?


Answer:

The voltage waveform produced by an AC generator is sinusoidal.

Question: What is another name for effective voltage?


Answer:

Root Mean Square (RMS) Voltage is another name for effective voltage.

Question: What does a "dead circuit" in Thevenin's and Norton's theorem mean?


Answer:

A "dead circuit" means that all independent sources have been zeroed out. Zeroing out a source means that independent voltage sources are converted to short circuits while independent current sources are converted to open circuits.

Question: What technique is applied to convert a Thevenin equivalent circuit into a Norton equivalent circuit or vice versa?


Answer:

Source transformation is applied. A voltage source in series with an internal resistance is equivalent to a current source in parallel with the same internal resistance.

V thevenin = (I norton) x (R internal)
I norton = (V thevenin) / (R internal)
R internal = (V thevenin) / (I norton)

Question: How many responses are obtained from an N number of independent sources present in a given circuit?


Answer:

N responses are obtained from an N number of independent sources.

Implication of a negative response in superposition

Question: What does a negative response in superposition imply?


Answer:

A negative response implies that the original assumed direction of current or polarity of voltage should be reversed.

Mesh and Nodal Analysis Principles

Question: What basic laws are the underlying principles of Mesh Analysis and Nodal Analysis?


Answer:

Kirchoff's Voltage Law (KVL) is the underlying principle used in Mesh Analysis.

Kirchoff's Current Law (KCL) is the underlying principle used in Nodal Analysis.

Implication of a negative mesh current

Question: What does a negative mesh current imply?


Answer:

A negative mesh current implies that the original assumed direction of current is wrong and is in the reverse direction of the actual current.

Maximum Power Transfer in DC Circuits

Question: When is the maximum power delivered from a practical source to a load?


Answer:

Maximum power is delivered to the load when its resistance is equal to the source's internal resistance.

Ideal current source resistance

Question: How much internal resistance does an ideal current source have?


Answer:

An ideal current source has infinite resistance.

Ideal voltage source resistance

Question: How much internal resistance does an ideal voltage source have?


Answer:

An ideal voltage source has zero resistance.

Current for full scale deflection

Question: What current is required for full scale deflection of a galvanometer having a current sensitivity of 50 micro-amperes per scale division? The meter has exactly 50 divisions on either side of the mid-scale index.


Answer:

There are two possible interpretations of the problem. One has a meter having a mid-scale index value of zero, a maximum positive current reading, and a maximum negative current reading.

To solve for the maximum positive value of current that will cause full scale deflection, simply multiply the current sensitivity by the number of divisions. In this case, 50 micro-amperes per scale division multiplied by 50 divisions will give 2500 micro-amperes or 2.5 mA.

The other interpretation is that a meter can read from zero to a maximum positive value of current, and that there are 100 divisions in between these two extremes. In this case, 50 micro-amperes per scale division multiplied by 100 divisions will give 5000 micro-amperes or 5 mA.

Computing the value of a shunt resistor

Question: Determine shunt resistance needed to convert a galvanometer to an ammeter with a full scale reading of 10 A if the scale requires 2.5 mA to cause full scale deflection with a coil resistance of 10 ohms?

Answer:

I original meter max = I full scale deflection = 2.5 mA
Using the current divider principle:
(I original meter max)/(I adjusted meter max)=(R shunt)/(R meter + R shunt)
(25 mA) / (10 A) = (R shunt) / (10 ohms + R shunt)
R shunt =  0.0251 ohms