Unit 7 Test

Three resistors, which measure 45Ω, 10Ω, and 30Ω are connected in series to a 24 V battery. The Req is 85Ω. The total current is 0.282 A. Find the voltage across each resistor.

12.69 V, 2.82 V, 8.46 V

What is the unit of resistance?

Ohms or V/A

Three identical resistors are wired in parallel with a battery. Each resistor has resistance R. Write an expression to find the Req of the circuit?

R/3

T/F: You have one light bulb connected to a battery so that the bulb is lit. If you add a second bulb to the circuit, in parallel, the voltage across the first bulb decreases.

false

T/F: You have one light bulb connected to a battery so that the bulb is lit. If you add a second bulb to the circuit, in parallel, the first bulb gets dimmer.

false

T/F: You have one light bulb connected to a battery so that the bulb is lit. If you add a second bulb to the circuit, in series, the first bulb gets dimmer.

true

T/F: You have one light bulb connected to a battery so that the bulb is lit. If you add a second bulb to the circuit, in series, the voltage across the first bulb decreases.

true

T/F: Current is defined as the rate of flow of energy in a circuit

false

T/F: Home electrical wiring is done in parallel so that each device receives the same current

false

T/F: In a parallel connection, the largest resistor will have the largest current

false

T/F: In regards to a series circuit, adding more light bulbs will not affect the brightness of the bulbs.

false

T/F: In regards to a series circuit, as more light bulbs are added, the total current increases

false

T/F: In regards to a series circuit, each bulb receives a different amount of current.

false

T/F: In regards to a series circuit, if one bulb is removed, the others will remain lit.

false

T/F: In regards to resistors wired in parallel, as more resistors are added, the current through the battery decreases

false

T/F: In regards to resistors wired in parallel, each resistor has a direct "line" to the battery, so they all receive the same current

false

T/F: In regards to resistors wired in parallel, the Req increases as more resistance is added

false

T/F: In regards to resistors wired in parallel, the smallest resistor will have the smallest current running through it

false

T/F: The conventional current is the current that always exits from the negative terminal of the battery

false

T/F: The total resistance in a parallel circuit increases as more resistors are added

false

T/F: The total resistance in a series circuit decreases as more resistors are added

false

T/F: The voltage is the same for all resistors that are connected in series

false

A lamp is left on for 24 hours a day. How much does she pay for electricity each month to light the 60W bulb? The company charges $0.08/kWh.

$3.46

Three resistors are connected in parallel. The resistors have a resistance of 1Ω, 2Ω, and 3Ω. The battery has a current of 765 mA. Find the current in the 2Ω resistor.

0.209 A

Three resistors, which measure 45Ω, 10Ω, and 30Ω are connected in series to a 24 V battery. The Req is 85Ω. Find the total current that travels through the circuit.

0.282 A

Suppose you always forget to turn off one of the 75W light bulbs in your kitchen. You leave it on for 24 hours a day. How much electrical energy do you use in a day to keep that bulb lit?

1.8 kWh

If a source has a current of 2.4A, how many Coulombs of charge pass through the source every second?

2.4 C

You have a 9V battery connected to two resistors in parallel with resistances of 6Ω and 3Ω. Find the total current.

4.5 A

A 3Ω resistor is connected to a 6V battery. An unknown resistor is added to the circuit in parallel. The total current with both resistors is 3.2A. What is the resistance of the unknown resistor?

5 Ohms

Suppose you have three resistors: 15Ω, 25Ω, and 30Ω. You can wire the resistors in series or in parallel. What do you get when they are in series?

70Ω

Suppose you have three resistors: 15Ω, 25Ω, and 30Ω. You can wire the resistors in series or in parallel. What do you get when they are in parallel?

7Ω

Three resistors, which measure 45Ω, 10Ω, and 30Ω are connected in series to a 24 V battery. Find the Req.

85 Ohms

You have a 9V battery connected to two resistors in parallel with resistances of 1Ω and 2Ω. The source current is 13.5A. Find the current through each resistor.

9 A, 4.5 A

Consider a circuit that contains three identical resistors. "If I arrange the three resistors in series, then each resistor gets the same amount of current. If i arrange them in parallel, they each get the same amount of current. Therefore, the total current in both circuits must be the same." Which parts of this statement are correct?

All resistors in series get the same amount of current. Identical resistors get the same amount of current in parallel.

Name the 3 units of power.

Hp, J/s, W

Suppose you have a battery connected to 7 identical resistors in parallel. Each resistor has resistance R. The source current is I. Write an expression to find the current through each resistor.

I/7

Consider a circuit that contains three identical resistors. "If I arrange the three resistors in series, then each resistor gets the same amount of current. If i arrange them in parallel, they each get the same amount of current. Therefore, the total current in both circuits must be the same." Which parts of this statement are incorrect?

Req is different in series and parallel circuits, therefore the total current in both circuits isn't the same.

Three resistors measure 45Ω, 10Ω, and 30Ω. Which resistor will dissipate the least amount of power?

Resistor 2

A kilowatt-hours measures...

energy

Consider a circuit that contains three identical resistors. How do you rearrange the circuit to make sure each resistor gets the maximum possible voltage?

parallel

Series, parallel, or both? The Req is always less than any resistor in the circuit

parallel

Series, parallel, or both? The largest resistor will use the least amount of power

parallel

You have three identical resistors. How do you wire the circuit to get the greatest possible current?

parallel

Series, parallel, or both? Current through the battery increases as more resistors are added

parellel

Series, parallel, or both? Current through the battery decreases as more resistors are added

series

Series, parallel, or both? Equivalent resistance is always greater than any resistor in the circuit

series

Series, parallel, or both? The largest resistor will use the greatest amount of power

series

Series, parallel, or both? The smallest resistor will receive the smallest voltage

series

T/F: Current can have units of C/s

true

T/F: Current is defined as the rate of flow of electric charges

true

T/F: Currents can only travel through closed loops, called circuits

true

T/F: Currents come in two "varieties" : AC and DC

true

T/F: Home electrical wiring is done in parallel so that each device receives the same voltage.

true

T/F: Home electrical wiring is done in parallel so that if many devices are running, the current is not reduced to unusable levels.

true

T/F: Home electrical wiring is done in parallel so that some devices may be on while others are off

true

T/F: In regards to a series circuit, as more light bulbs are added, the total current decreases

true

T/F: In regards to resistors wired in parallel, the Req decreases as more resistors are added

true

T/F: The conventional current is opposite to the actual current of electrons in a circuit

true

T/F: The conventional current is the current that always exits from the positive terminal of the battery

true

T/F: The conventional current is the direction of flow of positive charges in a circuit

true

T/F: The flow of current is different through resistors that are connected in parallel

true