Series Electrical Circuits and Parallel Electrical Circuits

In the parallel circuit at right, it is certain that ---.

• the ammeter shown reads 0.75 A

• the voltmeter shown reads 9.0 V

• the combined resistance is more than 24 Ω

• the voltmeter shown reads 4.5 V

Answer explanation

For parallel circuits, the voltage for the whole circuit and the voltage across each individual branch is the same number

The diagram shows a ---.

• series circuit

• parallel circuit

• combination circuit

• tangent circuit

Answer explanation

If there is only one path or loop on which current can flow, it is a series circuit.

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 is divided between the three light bulbs.

Answer explanation

The current coming out of the battery has no opportunity to divide or split up, so there is only one path or loop, making it a series circuit.

What is the equivalent resistance (a.k.a. total resistance) of the three resistors shown?

• 6 Ω

• 33 Ω

• 9Ω

• 3 Ω

Answer explanation

1/6 + 1/9 + 1/18 = 0.33333

1/0.33333 = 3.0

If one of the light bulbs in a series circuit is removed from its socket (the socket is left in place), what will happen to the other light bulbs?

• The other light bulbs will stay lit with the same brightness

• The other light bulbs will go out

• The other light bulbs will burn brighter

• Both light bulb will stay lit

Answer explanation

The current in a series circuit is the same everywhere. Unplugging a bulb forces the current in that bulb to be zero, making the current zero everywhere.

If one of the light bulbs in a parallel circuit is removed from its socket (the socket is left in place), what will happen to the other light bulbs?

• The other light bulbs will stay lit with the same brightness

• The other light bulbs will go out

• The other light bulbs will burn brighter

• Both light bulb will stay lit

Answer explanation

The current in any branch on a parallel circuits is independent of what is going on in the other branches.

The circuit shown contains a battery 12V, a 6.0 Ω resistor and two meters X and Y.

One meter records current and one meter records potential difference.

• meter X : 2.0 A

  meter Y : 12.0 V

• meter X : 2.0 V

  meter Y : 1.0 A

• meter X : 12.0 A

  meter Y : 2.0 V

• meter X : 12.0 V

  meter Y : 2.0 A

Answer explanation

Meter X is in series with the circuit element; ammeters must be placed in series.

Meter Y is in parallel with the circuit element; voltmeters must be placed in parallel.

Look at figure 4. Ammeter A₂ and A₃ read the same value at 0.40 A. What is the reading on ammeter A₁ (the one on top)?

• 0.40 A

• 0.20 A

• 0.80 A

• 0.00 A

Answer explanation

A1 is reading the total current, which got divided up between A2 and A3. A2 and A3 add up to what A1 is reading.

What is the relationship between the readings on ammeters A₁, A₂ and A₃?

• A₁ = A₂ + A₃

• A₃ = A₁ + A₂

• A₁ = A₂ = A₃

• A₃ = A₁ - A₂

Answer explanation

Series circuits have the same current everywhere.

Electric potential divided by current

(V / I) will be how you calculate ---.

• current

• power

• resistance

• watts

Answer explanation

V=IR