Circuits

Ohm's Law in Series and Parallel Circuits

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Multiple Choice

Ohm's Law describes how Voltage, Current, and Resistance are related by the equation I = V/R. Which equation would help us find resistance?

• R = V x I

• R = I / V

• R = V / I

Multiple Choice

What is resistance measured in?

• Ω (Ohms)
• V (Volts)
• A (Amps)
• W (Watts)

Multiple Choice

As the resistance of a circuit increases, the current will...

• increase
• decrease
• stay the same

Multiple Choice

Ohm's Law describes how Voltage, Current, and Resistance are related by the equation I = V/R. Which equation would help us find voltage?

• V = I x R

• V = I / R

• V = R / I

Multiple Choice

What is the Voltage of a circuit that has a resistance of 5 Ω and a current of 2 A?

• 25 V
• 10 V
• 2.5 V
• 0.4 V

2 Basic Types of Circuits:

• Series (one path for electrons)

• Parallel (more than one path for electrons to flow)

Multiple Choice

What kind of circuit is this?

• series
• parallel

Multiple Choice

The picture shows an electrical circuit. This circuit is a series circuit because:

• It has 3 light bulbs.

• The same current flows through all three light bulbs.

• It uses a single battery.

• The electrical current has more than one path to flow through

Voltage in Series Circuits

• The voltage drops each time it passes through a resistor (like a lightbulb)

• Total voltage equals the sum of all the voltage drops.

• V total = V₁ + V₂ + V₃ + V₄ ...

• Total Voltage also equals the voltages of all batteries placed in series

Multiple Choice

What is the total voltage of the battery if its 5 resistors produce the follwoing drops: 8V, 2V, 5V, 1.5V and 1.5V?

• 4.5 V.

• 9 V.

• 18 V.

• 36 V.

Voltage in Parallel

• The voltage is the same no matter which branch of the parallel circuit you're on.

• V_Total = V₁ = V₂ = V₃ = ...

• Like a platform with several water slides (paths down), no matter which one you choose, everyone ends back up at the bottom.

Multiple Choice

The following type of circuit has the same voltage throughout the entire circuit.

• series

• parallel

Current in Series

• The same current is shared by the whole circuit, since there's only one path for the electrons to go, so all the electrons go that way

• I_Total = I₁ = I₂ = I₃ = I₄ = I₅ = ...

Current in Parallel

• In parallel, the electrons will split and go down different paths, so only some will go down any given path

• This decreases the current through each path.

• Current will be faster where there's less resistance.

• Electrons regroup at the end, though, so... I_T = I₁ + I₂ + I₃ + ...

Multiple Choice

What is current?

• the amount of push the electrical source supplies to the circuit

• how much a given device resists the flow of electric current

• flow of electric charge

• none of the above

Multiple Choice

The current is the same throughout this type of circuit

• series

• parallel

Multiple Choice

A parallel circuit has 6 ohm, 10 ohm, 12 ohm and 15 ohm resistors. Which resistor will have the highest amount of current flowing through it?

• 15

• 12

• 10

• 6

Resistance in Series

• The more resistors you add, the more resistance overall.

• Adding more lightbulbs to this circuit would make each bulb dimmer and dimmer.

• R_Total = R₁ + R₂ + R₃ + R₄ ...

Multiple Choice

If we added a 4th lightbulb...

• the bulbs would get brighter

• the bulbs would turn off

• the bulbs would all get dimmer

• the bulbs would each have a different brightness

Multiple Choice

What is the total resistance of a series circuit with values of 5, 9, and 17 ohms?

• 31

• 765

• 17

• 3

Multiple Choice

What is the current of a series circuit with values of 5, 9, 17 ohms, with a battery of 12V

• 0.3871

• 3870.0

• 372.0

• 4.4395

Resistance in Parallel

• Total resistance decreases the more resistors you add in parallel

• It's like on Black Friday when the checkout line gets long and they add another checkout. There won't be as many people going through each line, but each person won't have the line holding them back as much.

• 1/R_T = 1/R₁ + 1/R₂ + 1/R₃ ...

Multiple Choice

Three resistors, $R_A=10\ \Omega$  , $R_B\ =20\ \Omega$  , and  $R_C\ =\ 25\ \Omega$  , are connected in PARALLEL. The total resistance of this setup is equal to _____.

•  $0.19\ \Omega$  

•  $5.26\ \Omega$  

•  $18.33\ \Omega$  

•  $55\ \Omega$  

Multiple Choice

Three resistors, $R_A=10\ \Omega$  , $R_B\ =20\ \Omega$  , and  $R_C\ =\ 25\ \Omega$  , are connected in SERIES. The total resistance of this setup is equal to _____.

•  $0.19\ \Omega$  

•  $5.26\ \Omega$  

•  $18.33\ \Omega$  

•  $55\ \Omega$  

Multiple Choice

The current going through the 90 ohm resistor is 

• 10 amps
• 0.1 amps
• 0.2 amps
• .06 amps

Multiple Choice

The total resistance in this type of circuit is always smaller than any of its single resistor.

• series

• parallel

Multiple Choice

In a parallel circuit, when one light goes out, the others stay on. Now that there are less paths for the electrons, is there more or less total resistance?

• more (more backed up electrons, since there are less options for them to go)

• less

• the same

Multiple Choice

In a parallel circuit, when one light goes out, the others stay on. Would they get brighter or dimmer?

• brighter

• dimmer

• stay the same