Chapter 19 Flashcards
Explain why birds can sit on power lines safely even though teh wires have no insulation around the, whereas leaning a metal ladder up against a power line is extremely dangerous
There is only a tiny amount of potential difference between the eh birds feet because they are close together on the wire. When you put a metal ladder up against a power line you provide a direct connection between the high pop potential voltage line and the ground. The ladder will have a larger voltage difference between the top and bottom and a person on the ladder can have a large current through their body.
Discuss the advantages and disadvantages of CHristmas tree lights connected in arable land versus those connected in series
Series- same current so less wire but if one goes out they are all out. In parallel they each get the total voltage and if one goes pout the rest remain lit takes more wire.
If all you have is a 120 V line would it be possible to light several 6V lamps without burning them out? How?
20 6V lights in series
Two light bulbs of resistance r1 and r2 where r2 greater than r1 dand a battery connect in series. Which bulb is brighter, what if they are connected in parallel
Series if the light bulbs are in series, then each will have the same current. The power dissipated by the bulb as heat and light is P=I^2R so the bulb with the greater resistance R^2 will be brighter. Parallel if the bulbs are in parallel then each will have the same voltage. The power dissipated by the bulbs as heat and light is P=V^2/R and the bulb with the lower resistance R1 will be brighter.
Household outlets are often double outlets. Are these connected in series or parallel? How do you know?
Parallel. You can use both or one outlet and each will get the total voltage
With two identical light bulbs and two identical batteries explain how and why you would arrange the bulbs and batteries in a circuit to get the maximum possible total power to the ligh bulbs. Ignore internal resistance of batteries
Connect the batteries in series and connect the light bulbs in parallel. In series the voltage of the batteries add so you double the potential difference voltage. With the light bulbs in parallel you have less resistance and each will receive the total voltage.
If two identical resistors are connected in series to a battery does the battery have to supply mother power or less power than when only one of the resistors is connected, explain
Series the battery has to supply less power when the two resistors are in series P=V^2/R so if V is constant and R increases then the power decreases.
You have a single 60W bulb lit in your room how does the overall resistance of your rooms electric circuit change wen you turn on an additional 100W bulb explain
Teh resistance decreases since the circuit will be in parallel
Why is an appliance cord with three prong plug safer than one with two prongs
The third prong ground the case soo the case cannot reach a high voltage
If ammeters and voltmeters are not significantly alter the quantities they are measuring
The resistance of an ammeter should be much lower and the resistance of teh voltmeter should be be much higher than those of the circuit being measured, in series the ammeter is higher and in parallel the voltage is higher
