# When the series circuit shown to the right is connected, Bulb A is brighter than Bulb B. If the positions of the bulbs were reversed, 1. bulb A would again.

## Presentation on theme: "When the series circuit shown to the right is connected, Bulb A is brighter than Bulb B. If the positions of the bulbs were reversed, 1. bulb A would again."— Presentation transcript:

When the series circuit shown to the right is connected, Bulb A is brighter than Bulb B. If the positions of the bulbs were reversed, 1. bulb A would again be brighter. 2. bulb B would be brighter. 3. either of the above could occur. Ch 23-2 Thanks to Dean Baird.

When the series circuit shown to the right is connected, Bulb A is brighter than Bulb B. If the positions of the bulbs were reversed, 1. bulb A would again be brighter. 2. bulb B would be brighter. 3. either of the above could occur. Ch 23-2 Thanks to Dean Baird. Answer: 1 The bulbs are connected in series, so the same current passes through both of them. Different brightness indicates different filament resistance. Bulb A is NOT brighter because it is “first in line” for current from the battery! After all, electrons deliver the energy, and they flow from negative to positive—in the opposite direction!

Roll a piece of modeling clay into a cylinder and use an ohmmeter to measure its resistance. Now roll it out again until it's twice as long, and measure the resistance again. Compared with the initial resistance, the new resistance is Ch 23-3 Thanks to Peter Hopkinson. 1. unchanged. 2. twice as much. 3. four times as much. 4. eight times as much. 5. actually less.

Roll a piece of modeling clay into a cylinder and use an ohmmeter to measure its resistance. Now roll it out again until it's twice as long, and measure the resistance again. Compared with the initial resistance, the new resistance is Ch 23-3 Thanks to Peter Hopkinson. Answer: 3 Resistance is greater due to the smaller cross-section of the clay, and also greater due to its greater length. Its cross-section is half (increasing resistance by 2), and its length is doubled (increasing resistance by another 2), so resistance is four times as much. 1. Unchanged. 2. twice as much. 3. four times as much. 4. eight times as much. 5. actually less.

The 40-watt bulb and the 100-watt bulb are connected in series to the battery. Which bulb will glow brighter? 1. 40-watt bulb watt bulb Ch 23-6

The 40-watt bulb and the 100-watt bulb are connected in series to the battery. Which bulb will glow brighter? 1. 40-watt bulb watt bulb Ch 23-6 Answer: 1 The 40-watt bulb will glow brighter when connected in series. To understand this you must first understand that the filament in a 40-watt bulb is thinner and therefore of higher resistance than the filament of a 100-watt bulb. It is the higher resistance of the 40-watt bulb that keeps the current of only 40/100 the current in a 100-watt bulb when both are properly connected in parallel. Then more current flows in the 100-watt bulb and it glows brighter. But when connected in series, the current is less but is the same in each. The same amount of current “squeezing” through the finer filament of the 40-watt bulb heats it more and makes it glow brighter than the lower resistance 100-watt bulb.

Which circuit draws the most current?
B Which circuit draws the most current? Ch 23-7 1. Circuit A 2. Circuit B 3. Both the same

1. Circuit A 2. Circuit B 3. Both the same
Which circuit draws the most current? Ch 23-7 Answer: 3 This is one of those “tricky” circuits wherein the equivalent resistance for both circuits is the same. In fact, if you continue the sequence of a pair of 1- resistors in series connected in parallel to a 2- resistor at the right end of the circuit, the equivalent resistance would still be 1 . 1. Circuit A 2. Circuit B 3. Both the same

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