Quick Quizzes Dave Shattuck ECE 1100

Quick Quiz 2 (TuTh F2001) Take out a sheet of paper. Print your name on it. Imagine that Texas and California are connected by a transmission line. Sketch this. (Labeled boxes will do.) Define a voltage variable which is the voltage at California, with respect to Texas. Define a current variable which is the current flowing from Texas to California. If the voltage in Texas is 100[kV] higher than in California, find the value of your voltage variable. If the current flowing from California to Texas is 5[kA], find the value of your current variable.

Quick Quiz 1 – MW 9AM Fall 2001 Take out a sheet of paper. Print your name on it. Sketch a rough diagram of a cockroach. Define a voltage variable which is the voltage at the head, with respect to the tail. Define a current variable which is the current flowing from the tail to the head. If the voltage at the tail is 50[V] higher at the tail than at the head, find the value of your voltage variable. If the current flowing from the tail to the head is 5[A], find the value of your current variable.

Desk of Power Quiz Fall 2001 (MW 9AM) During the preparation for the mayoral debate, it was found that the desk for one of the candidates had a voltage across it, and a current through it. The voltage and current that existed for the desk are shown in the figure below. Write an expression for the power being absorbed by the desk. Find the power absorbed by the desk.

Desk of Power Quiz During the preparation for the upcoming presidential debate, it was found that the desk for one of the candidates has a voltage across it, and a current through it. The voltage and current that exist for the desk are shown in the figure below. a)      Is the desk absorbing power? b)      Write an expression for the power being absorbed by the desk.

Desk of Power Quiz a) Is the desk absorbing power? b)      Write an expression for the power being absorbed by the desk. Solution: a) In the first part of this problem, there is an assumption being made. The question “Is the desk absorbing power?” is assumed to really mean, “Is the desk absorbing positive power?” To answer this, we need to find the power associated with the desk, which is part b). So, let’s find it. Let’s start by determining which sign convention is being used. Just for clarity, I am going to define a couple of variables.

Desk of Power Quiz We have defined a couple of variables. The reference polarity of the current, is in the direction of the reference voltage rise. This is what we call the active sign convention. From our rules, then, we can write

Desk of Power Quiz Notice that we use a subscript to make it clear that we are writing an expression for the power being absorbed by the desk. We can now plug in the values for voltage and current, and get

Desk of Power Quiz Using this answer, we can answer part a). The answer is no, the desk is not absorbing positive power. It is delivering positive power. It is absorbing negative power. This is another way of saying that the desk is acting like a source, in that it is delivering power to the electrical circuit that it is connected to.

Quick Quiz 3 Tu-Th 4:30PM Section Take out a sheet of paper. Print your name on it. Imagine that Dr. Dave has a voltage across him, and a current through him. Sketch a picture of Dr. Dave, labeling his right and left hand. (A stick figure will do.) Define a voltage variable which is the voltage at his right hand, with respect to his left hand. Define a current variable which is the current flowing from his left hand, through his body, to his right hand. Write an expression for the power absorbed by Dr. Dave using your variables. If the voltage is 3[V] higher at his right hand than at his left hand, and the current flowing from his right hand to his left hand is 6[mA], find the power absorbed by Dr. Dave.

Electric Candidates Quiz Let’s do another quiz. Get out a sheet of paper.

Electric Candidates Quiz Find a numerical expression for the power delivered by each of the candidates.

Quick Quiz 3 MW 9AM Take out a sheet of paper. Print your name on it. Draw the schematic symbol for an independent voltage source. The value for this source is 15[V]. Label the terminal of the voltage source that is nearest the + sign, with the letter A. Label the terminal of the voltage source that is nearest the - sign, with the letter B. Define a current variable which is the current from terminal B to terminal A, through the voltage source. Write an expression for the power delivered by this voltage source, in terms of the this current variable. If a current equal to 2[mA] is flowing from terminal A to terminal B through the voltage source, find the power delivered by the voltage source.

Quick Quiz 4 TuTh 4:30PM Find a numerical expression for the power delivered by each of the batteries.

Quick Quiz 1 (Spring 2002) Take out a sheet of paper. Print your name on it. Sketch a picture of Sarah Hughes. (Artistry does not matter. A stick figure will do.) Define a voltage variable which is the voltage at her left hand, with respect to her right hand. Define a current variable which is the current flowing through her, from her right hand to her left hand. If the voltage at her right hand is 100[mV] higher than at her left hand, find the value of your voltage variable defined in 2. If the current flowing from her left hand to her right hand is 5[mA], find the value of your current variable defined in 3.

Baseball Facts barrel handle The World Series, which includes teams from only two countries, begins this weekend. In the baseball bat shown below, the end that you hold onto, is called the handle. The end which hits the ball is called the barrel. See the diagram below. barrel handle

Quick Quiz 1 (Fall 2002) Take a 3x5 card. Print your name on it. Sketch a baseball bat, and label the barrel and the handle. Define a voltage variable which is the voltage at the barrel, with respect to the handle. Define a current variable which is the current flowing through the bat, from the handle to the barrel. If the voltage at the barrel is 30[V] higher than at the handle, find the value of your voltage variable defined in 2. If the current flowing from the barrel to the handle is 5[mA], find the value of your current variable defined in 3.

Electric Companies Quiz Let’s do another quiz. Get out a sheet of paper. + -800[A] + Enron Reliant - 500[A] 220[V] 80[V] -80[V] - - + 300[A] - Dynegy Williams - Dr. Dave 470[V] 330[V] -300[A] + +

Electric Companies Quiz Find a numerical expression for the power delivered by each of the electric companies. + -800[A] + Enron Reliant - 500[A] 220[V] 80[V] -80[V] - - + 300[A] - Dynegy Williams - Dr. Dave 470[V] 330[V] -300[A] + +