Warm - Up What type (series or parallel) of circuit is circuit A? Support your answer. What type (series or parallel) of circuit is circuit B? Support your answer B A

Series vs Parallel - what do you remember?

Three Levels of Reading We are going to read information from the text book. YOU are going to come up with questions from the text. We are going to do something called: Three Levels of Reading.

CLOSE READERS: Reading on the lines (literal), Look BEYOND the plot for DEEPER LAYERS of MEANING The three layers of reading are: Reading on the lines (literal), Reading between the lines (inferential), Reading beyond the lines (evaluative).

The First Level Readers find meaning is found DIRECTLY in the text: you can literally put a finger in the reading and POINT TO THE ANSWER. Answers questions “Who?”, “What?”, “When?”, and “Where?”

The Second Level Readers INTERPRET what is in the text. Readers REASON, COMPARE, & CONTRAST, CLASSIFY, ANALYZE. Readers look for what passages REPRESENT or SUGGEST. The exact answer CANNOT be found directly in the text: the answer is “between the lines”. Key questions include “How?”, and “Why?”

THE THIRD LEVEL The third level is SUPER abstract. The answers are found beyond the lines. Readers move beyond the text to connect to UNIVERSAL MEANING. Key questions include “Why is this important?” “How does this text connect with my life? With all human beings?” Readers move BEYOND THE “WHAT?” to the “SO WHAT?”

Let’s Try it Together Open your book to p. 147 Read the text on p. 147

On the Line Questions Recall: These are questions that can be answered by finding the words on the page. My Question: “What law can we use to find current if we are given voltage and resistance?” You Try

Between the Lines Recall: What is represented or suggested by the text? Answers cannot be found directly on the page. You have to give an interpretation to answer the question. My Question: “How does law of conservation of energy explain why batteries eventually die?” “What is the difference between voltage and voltage drop?” You Try:

Beyond the Lines Recall: Connect the reading to universal meaning. Why is this information important and how does it connect to my life? My Question: “How does understanding how we use energy help me understand our energy crisis?” You try

P. 148-149 Read pages 148-149 Come up with 2 On the lines questions 1 between the lines question 1 beyond the lines question

P. 150-151 Read the pages. Find 2 sentences that are “striking” to you Meaning – you think they are significant or unexpected information.

Summary Information

Current in Series Measure current using an ammeter The current is the same everywhere in a series circuit. It does not matter where you put the ammeter, it will give you the same reading. All three ammeters give the same reading in this series circuit.

Adding more cells (increasing voltage) The current in a series circuit depends upon the number of cells. The more cells you add, the greater the current. It also depends on the number of resistors in the circuit – more resistors (i.e. light bulbs = less current flowing through the bulb = dimmer bulb.)

Current is NOT used up You might think that the current gets less as it flows through one component after another. But it is not like this. The current is not used up by the components in a circuit. This means that the current is the same everywhere in a series circuit, even if it has lots of lamps or other components.

Current in Parallel Charge divides up into separate branches such that there can be more current in one branch than there is in another. When taken as a whole The total amount of current in all the branches when added together is the same as the amount of current at locations outside the branches. The rule that current is everywhere the same still works, only with a twist.  

Ohm's Law

Ohm’s Law Describes how voltage, resistance, and current are related. Current = Voltage / Resistance I = V/R V = IR R = V/I Resistance and currant are indirectly related. Voltage and current are directly related. What happens to current if Voltage is increased? What happens to current if Resistance is increased? Note: When you have more than one resistor (i.e. light bulb) you have to find equivalent resistance before using Ohm’s Law.

Example Problem: A light bulb with a resistance of 2 ohms is connected to a 1.5 V battery as shown. Calculate the current that will flow.

You Try One: If a toaster produces 12 ohms of resistance in a 120 volt circuit, what is the amount of current in the circuit?

Electrical Power Previously, we learned mechanical power is the rate at which work is done. Electrical Power is rate of energy usage Power = Voltage x Currant P = VI Still measured in Watts.

Example Problem: A toaster oven has a power rating of 750 watts. If the oven heats a piece of pizza for 360 seconds, how many joules of energy have been used by the toaster oven?

You try one: The current flowing through an electric circuit is 9A. If the voltage is 120 V, what is the power of the circuit?

Using Electrical Power Electrical Power can be transformed in many different forms: Electric motors take electrical power and make mechanical power Light bulbs turn electrical power into light Toaster ovens turn electrical power into heat

Reading an Electric Bill Utility companies charge customers by kilowatt-hours (kWh). 1 kWh means 1000 W were used in 1 hour. Fun Facts – how much does it cost to run your technology (per year): Charging your cell phone: $.25 Charging an iPad: $1.50 Playing an Xbox: $42 Big Screen TV: $40

HW Work on the Ohm’s Law & Power problems