Chapter 8.9 Electric Circuits

Question 1

What is a circuit?

Answer 1

Any path along which electrons can flow

Question 2

What must there be fore a continuous flow of electrons?

Answer 2

There must be a Complete Circuit with No Gaps

Question 3

What usually constitutes a gap in electrical circuits?

Answer 3

An electric switch that can be opened or closed to either cut off energy or allow energy to flow

Question 4

In what two ways are devices commonly connected in a circuit?

Answer 4

In Series or in Parallel

Question 5

How are devices connected in a Series?

Answer 5

They form a single pathway for electron flow between the terminals of the battery, generator, or wall outlet

Question 6

How are devices connected in Parallel?

Answer 6

They form branches, each of which is a separate path for the flow of electrons

Question 7

Does the current pile up or accumulate in any of the three lamps in a simple circuit?

Answer 7

No it flows through each lamp almost immediately in each

Question 8

What would happen if there was a break anywhere in the path of the electrons? (Switch opening)

Answer 8

It would be an open circuit, and the flow of electrons would cease

Question 9

In a series circuit, is the current passing through each electrical device the same or different?

Answer 9

It is the same because electric current has a single pathway through the circuit

Question 10

In a series circuit, how do you find the total resistance to current in a circuit?

Answer 10

You add the resistance of all the individual devices to find the sum of the individual resistances along the circuit path.

Question 11

Is the total voltage impressed across a series divided among the individual electrical devices?

Answer 11

Yes
The sum of the voltage drops across the resistance of each individual device is equal to the total voltage supplied by the source

Question 12

The sum of energies given to each device is equal to what?

Answer 12

The amount of energy given to the total current

Question 13

What is the voltage drop across each device proportional to?

Answer 13

The voltage drop across each device is proportional to its resistance

Question 14

What happens to the brightness of each lamp in a series circuit when more lamps are added to the circuit?

Answer 14

This produces a greater circuit resistance. This decreases the current in the circuit and therefore in each lamp, which causes the dimming of the lamps. Energy is divided among more lamps, so the voltage drops across each lamp is less.

Question 15

What is Voltage Drop?

Answer 15

The amount of voltage loss that occurs through all or part of a circuit due to impedance

Question 16

What is the main disadvantage of a series circuit?

Answer 16

If one device fails, current in the entire circuit ceases

Question 17

In a parallel circuit, is the voltage the same across each device?

Answer 17

Yes

Question 18

In a parallel circuit, does the current divide among the parallel branches?

Answer 18

Yes

Because the voltage across each branch is the same, the amount of current in each branch is inversely proportional

Question 19

The amount of current in each branch is inversely proportional to what?

Answer 19

The resistance of the branch

Question 20

What is the sum of the currents through each of the parallel branches equal to?

Answer 20

The sum of the current in each parallel branch is equal to the original current through the voltage source

Question 21

When you add a parallel branch, is overall resistance increased or decreased?

Answer 21

Overall resistance is lowered with each added path between any two points of the circuit

Question 22

Is the overall resistance of the parallel circuit greater than or less than the resistance of any one of the branches?

Answer 22

It is less than

Question 23

In a parallel circuit, what happens to the current in the other lamps if one of the lamps in a parallel circuit burns out?

Answer 23

If one burns out, the others are unaffected.
Because neither voltage nor resistance (Ohm’s law) is affected in the other branches, the current in those branches is unaffected.

Question 24

In a parallel circuit, what happens to the brightness of each lamp when more lamps are added in parallel to the circuit?

Answer 24

The brightness of each lamp is unchanged as other lamps are introduced (or removed). Only the total resistance and total current in the total circuit changes, which means that the current in the battery changes.

Question 25

What is an overloaded circuit?

Answer 25

Circuits that carry more than a safe amount of current

Question 26

Electricity is usually fed into a home by way of what?

Answer 26

Two wires called Lines.

They are very low in resistance and are connected to wall outlets in each room

Question 27

How do you prevent overloading in circuits?

Answer 27

Connect fuses in a series along the supply line or use circuit breakers, which use magnets to open a switch when the current is excessive

Question 28

In a series circuit, the total resistance of the circuit is equal to what?

Answer 28

It’s equal to the sum of the values for the individual resistors

Question 29

In a parallel circuit, is the total resistance greater than or less than the sum of the individual resistors?

Answer 29

The total resistance of the circuit is less than the sum of the resistors.
Because the current has more pathways to go through, there is less resistance