PHYSICS CIRCUITS

Study the three loops shown below. For each loop, state which of the bulbs will light.

1. Neither 2. bulb a 3. both bulbs

What is the difference between conductors and insulators?

A CONDUCTOR ALLOWS CHARGE TO FLOW THROUGH IT. AN INSULATOR DOES NOT ALLOW CHARGE TO FLOW THROUGH IT.

How does the flow rate of charge into a parallel circuit divide when different branches have different resistances

A GREATER FRACTION OF THE INCOMING FLOW RATE GOES TO THE BRANCHES WITH LOWER RESISTANCE

You should have observed in several activities that as soon as a very small gap is produced anywhere in the circuit, the bulbs go out. What does this tell you about air being a conductor or an insulator?

AIR MUST BE AN INSULATOR

Is the electric pressure inside a capacitor most like air pressure or water pressure? Explain your reasoning.

AIR PRESSURE. WATER CANNOT BE COMPRESSED EVEN WHEN IT APPEARS TO BE FULL. AIR CAN BE COMPRESSED TO MAKE ROOM FOR MORE.

A good measuring instrument should have as little interference as possible on the system being measured. Describe: how each meter should be connected in a circuit in relation to the circuit elements (in series or in parallel)

AMMETER - IN SERIES VOLTMETER - IN PARALLEL

A good measuring instrument should have as little interference as possible on the system being measured. Describe: whether the resistance of an ammeter and a voltmeter is high or low

AMMETER - LOW RESISTANCE VOLTMETER - HIGH RESISTANCE

In the circuit below, which bulb lights first? a. Bulb A b. Bulb B c. Bulb C d. They all light at the same time

D

A circuit consists of three batteries and two identical bulbs in series. True or false: When the circuit is connected, the bulb closer to the positive end of the battery terminal lights before the other bulb.

FALSE. BOTH BULBS LIGHT AT THE SAME TIME.

A circuit consists of three batteries and two identical bulbs in series. True or false: The bulb closer to the positive end of the battery terminal will be brighter than the other bulb.

FALSE. THE BULBS WILL BE EQUALLY BRIGHT.

What happens to flow rate of charge in a circuit as more bulbs are added in series? What is your evidence?

FLOW RATE OF CHARGE DECREASES; DECREASED BRIGHTNESS OF BULBS (OR LESS COMPASS DEFLECTION)

You are given two bulbs. When used in a circuit to charge and discharge the blue capacitor you note that these new bulbs stay lit longer than the long bulbs had (using the same battery and capacitor). Do the new bulbs have a higher or lower resistance than long bulbs? Explain your reasoning.

HIGHER RESISTANCE. THE LONGER LIGHTING TIME INDICATES A DECREASED FLOW RATE.

You are given two new bulbs. When used in a circuit to charge and discharge the blue capacitor you note that these new bulbs stay lit longer than the long bulbs had. Do the new bulbs have a higher or lower resistance than long bulbs? Explain your reasoning.

HIGHER RESISTANCE. THE LONGER LIGHTING TIME INDICATES A DECREASED FLOW RATE.

In terms of electric pressure, when does a capacitor charging occur? When does charging stop?

IF THERE IS A PRESSURE DIFFERENCE BETWEEN THE PLATES OF A CAPACITOR AND THE TERMINALS OF A BATTERY TO WHICH THE PLATES ARE CONNECTED, THEN THE CAPACiTOR WILL CHARGE. IT STOPS CHARGING WHEN THE CAPACITOR PLATES ARE AT THE SAME PRESSURES AS THE BATTERY TERMINALS TO WHICH THEY ARE CONNECTED.

Why does it make sense to believe that a wire can also be a source of moving charge?

IT'S A CONDUCTOR (METAL CAPACITOR FLATES ARE A SOURCE OF MOVING CHARGE, AND WIRES ARE MADE OF METAL...)

Knowledge of the flow rate provides what information about the speed of each bit of moving charge?

KNOWLEDGE OF THE FLOW RATE PROVIDES NO INFORMATION ABOUT THE SPEED OF EACH BIT OF MOVING CHARGE.

Given 3 of the same kind of bulbs, how could you combine them to get the maximum total resistance? The minimum total resistance?

MAXIMUM- ALL 3 IN SERIES; MINIMUM- ALL 3 IN PARALLEL

Is there any place where you can break the loop and any bulb will still stay lit?

NO

How many bulbs will light in the circuit below?

ONLY THE LOWER TWO BULBS LIGHT

What stops a capacitor charging?

PRESSURE IN THE CAPACITOR PLATES

Explain the difference between rate and speed.

RATE- AN AMOUNT OF SOMETHING PER UNIT TIME SPEED- DISTANCE PER UNIT TIME (A SPECIFIC EX: OF RATE)

Does a light bulb filament control the amount of charge that passes through it of does it control the rate at which charge flows? What is your evidence?

RATE; DIFFERENT LIGHTING TIMES FOR THE SAME AMOUNT OF CHARGE STORED IN A CAPACITOR

TRUE/ FALSE: Any conductor with very low resistance is unable to maintain a pressure difference inside itself.

T

In terms of electric pressure, what does it mean to say that there is a "voltage drop" between two points?

THAT THERE IS AN ELECTRIC PRESSURE DIFFERENCE BETWEEN THE TWO POINTS

How does the process of discharging provide evidence that charge was stored in the upper plate of the capacitor during charging?

THE CHARGE THAT MOVED DURING DISCHARGING COULDN'T HAVE COME FROM THE BATTERY SO MUST HAVE COME FROM SOME NON-BATTERY PART OF THE CIRCUIT.

The direction of conventional flow is stated as flowing out of which terminal and into which terminal of the battery?

THE DIRECTION IS OUT OF THE "+" TERMINAL AND INTO THE "-" TERMINAL.

What determines the electric pressure inside a wire?

THE ELECTRIC PRESSURE IN A WIRE IS DETERMINED BY THE PRESSURE IN A BATTERY TERMINAL OR CAPACITOR PLATE TO WHICH IT IS CONNECTED.

How does the flow rate of charge into a parallel circuit divide when all branches of the circuit have the same resistance?

THE FLOW RATE IS EQUAL IN ALL BRANCHES THAT HAVE THE SAME RESISTANCE

What is the relationship between the flow rate of charge in the trunk wire of a house and the flow rate of charge in the branch wires (going to different rooms) that are connected to the truck wire?

THE FLOW RATE OF CHARGE IN A TRUNK WIRE IS THE SUM OF THE FLOW RATES OF CHARGE IN THE BRANCH WIRES DIRECTLY ATTACHED TO IT

What effect does a wire connected in parallel with a light bulb or other circuit element have on the flow of rate of charge across that element?

THE FLOW RATE THROUGH THAT ELEMENT BECOMES ZERO, WITH ALL MOVING CHARGE NOW FLOWING AROUND IT - THROUGH THE SHORTING WIRE

What effect does a wire connected in parallel with a light bulb or other circuit element have on the electric pressure difference across that element?

THE PARALLEL WIRE REDUCES THE PRESSURE DIFFERENCE ACROSS THAT ELEMENT [ZERO?]

Assuming that something flows through wires when bulbs are lit in a circuit, is the direction of the flow the same in all the wires, or does it vary in different parts of the circuit? Why do you think so?

THE SAME—COMPASS DEFLECTIONS (OR CHAOS IN WIRES IF CURRENT WENT IN DIFFERENT DIRECTIONS)

How do we know that long bulbs have more resistance than round bulbs?

THERE IS A LOWER FLOW RATE OF CHARGE MOVING THROUGH THE LONG BULBS BECAUSE OF THE LONGER LIGHTING TIME.

A circuit consists of three batteries and two identical bulbs in series. True or false: If the second bulb is removed from its socket, the first bulb will go out.

TRUE

True or False (and state evidence which either supports or contradicts each statement): The battery determines the direction of flow of charge in a circuit

TRUE. IF THE WIRES CONNECTED TO THE BATTERY ARE REVERSED, THE COMPASS NEEDLE DEFLECTION WILL ALSO BE REVERSED.

A circuit consists of three batteries and two identical bulbs in series. True or false: Charge flows at the same rate through both bulbs.

True

Explain what electrical quantity of each of the two meters measures, and what units are used for the measurements.

VOLTMETER MEASURES ELECTRICAL PRESSURE DIFFERENCE (VOLTAGE OR POTENTIAL DIFFERENCE); UNITS ARE VOLTS AN AMMETER MEASURES THE FLOW RATE OF CHARGE (CURRENT); UNITS ARE AMPERES (AMPS)

Does a battery have resistance? What is your evidence?

YES- (BRIGHTNESS OF BULB)

A circuit has two bulbs lit. Is the circuit a continuous conducting path? What is the evidence?

YES- THE BULBS LIGHT

Consider a circuit with a capacitor, battery, wire, and bulb. Describe the source(s) of charge during: a. capacitor charging b. capacitor discharging

a. ALL CONDUCTING COMPONENTS OF THE CIRCUIT [BATTERY] b. SAME AS ABOVE NOT THE BATTERY [CAPACITOR]

A circuit contains one battery and two bulbs in parallel. When a second battery of the same voltage is connected in parallel to the first battery, is there an increase, decrease, or no change in the electric pressure difference across the first battery?

no change

A single bulb is connected to a fresh battery. When a second bulb is added in parallel to the first bulb, is there an increase, decrease, or no change in the electric pressure difference across the battery?

no change

Besides the bulbs lighting, what is your evidence that something happens in the wires when the bulbs are lit?

the compass deflects

What are the minimum components a circuit must contain in order to charge a capacitor?

BATTERY, CAPACITOR, WIRES, [BULBS]

What materials and conditions must be present for a bulb to light?

BATTERY, WIRES, BULB, UNBROKEN LOOP

Why is a wire considered to have the same electric pressure everywhere inside itself?

BECAUSE ITS RESISTANCE IS NORMALLY SO LOW THAT IT CANNOT MAINTAIN ANY SIGNIFICANT PRESSURE DIFFERENCE BETWEEN ONE END OF THE WIRE AND THE OTHER. NOTE- THIS DEPENCDS ON THE LENGTH AND THICKNESS OF THE WIRE AND ON THE MATERIAL OF WHICH IT IS MADE. A VERY LONG CONNECTING WIRE CAN HAVE APPRECIABLE RESISTANCE, AND THE FILAMENT INSIDE A BULBS IS MADE OF MATERIAL THAT HAS HIGH RESISTANCE. THE WIRES IN THIS QUESTION ARE ASSUMED TO BE ORDINARY SHORT CONNECTING WIRES.

In the circuit shown below, bulb A and bulb B are identical and of equal brightness. They both have high resistance. If another identical bulb (C) is added to the circuit as shown in the second circuit, what happens to the brightness of bulb A? bulb B?

BOTH A AND B BECOME DIMMER

In terms of electric pressure, when does a bulb light? When does it stop lighting?

BULBS LIGHT WHEN THERE IS A DIFFERENCE IN ELECTRIC PRESSURE BETWEEN THE WIRES CONNECTED TO IT; IT STOPS WHEN THERE IS EQUAL PRESSURE ON EACH SIDE.

Study the two circuits below in which a paper clip has been inserted between wires in a circuit. Which of the following statements is (are) true?a. The bulb will light more brightly in circuit A b. The bulb will light more brightly in circuit B c. The bulb will be the same brightness in either case. d. The bulb will not light.

C. THE BULB WILL BE THE SAME BRIGHTNESS IN EITHER CASE.

How would Benjamin Franklin have described the condition of the plates in a charged capacitor compared with the plates in an uncharged capacitor?

CHARGED- POS. PLATE HAS MORE CHARGE; NEG. PLATE HAS LESS CHARGE UNCHARGED- BOTH PLATES HAVE THE NORMAL AMOUNT OF CHARGE

What is the difference in speed and current?

CURRENT MEANS RATE OF FLOW AND NOT THE SPEED OF MOVEMENT.