Three identical light bulbs are connected in series, then are disconnected and arranged in parallel. For each of the scenarios below indicate what changes (if any) take place

A. Total resistance of the circuit
B. Total current of the circuit
C. Power dissipated by the circuit
D. Voltage used by one of the light bulbs
E. Resistance of one of the light bulbs

I will be happy to check your thinking.

A. series R=r+r+r parallel 1/r=1/r+1/r+1/r

B. series R=R1+R2+R3 Parallel 1/R= 1/r1+1/r2+1/r3

C. p=1xV=90 mA x 9V=0.81W

D. 3(1/3) Ax120 V= 120 W)

Are those right so far ?

A. you get the idea, but results can be simplified further

Since the bulbs are identical each with resistance r, then
in series, R=3r,
in parallel, 1/R=(1/r+1/r+1/r)=3/r, in other words, R=r/3.

B. Current = i, governed by V=iR.
For light bulbs in household circuit, V is constant, so i=V/R.
Retry using R calculated in A.

C. Power is Vi
Use results obtained in B, and multiply by V to express power in terms of V and R.

D. V=ir
In series, voltages is equally dropped over the three bulbs, so voltage drop of each is V/3.
In parallel, the voltage is the same across all bulbs, so V.

E. I'll leave that to you.

To analyze the changes in the given scenarios, we need to understand the concepts of series and parallel connections in electrical circuits.

Series connection:
When three identical light bulbs are connected in a series, the positive terminal of one bulb is connected to the negative terminal of the next bulb. The current flowing through all the bulbs is the same, and the total resistance of the circuit is the sum of the individual resistances of the bulbs.

Parallel connection:
When the three identical light bulbs are disconnected and arranged in parallel, each bulb is connected to the positive and negative terminals directly. The voltage across each bulb is the same, and the total resistance of the circuit is calculated using the formula: 1/Total resistance = 1/R1 + 1/R2 + 1/R3, where R1, R2, and R3 are the resistances of the individual bulbs.

Now, let's analyze the changes for each scenario:

A. Total resistance of the circuit:
- Series connection: The total resistance of a series connection is the sum of the individual resistances of the bulbs. So, in this case, the total resistance would be R_total = R1 + R2 + R3 (since the bulbs are identical).
- Parallel connection: The total resistance of a parallel connection is given by the formula mentioned earlier. So, in this case, the total resistance would be 1/R_total = 1/R1 + 1/R2 + 1/R3.

B. Total current of the circuit:
- Series connection: In a series connection, the current passing through each bulb is the same. So, the total current flowing through the circuit will also be the same as the current flowing through each bulb.
- Parallel connection: In a parallel connection, the total current flowing through the circuit is the sum of the currents flowing through each individual bulb.

C. Power dissipated by the circuit:
- Series connection: The power dissipated by each bulb in a series connection is the same, as the current passing through each bulb is the same. So, the total power dissipated by the circuit is the sum of the powers dissipated by the individual bulbs.
- Parallel connection: The power dissipated by each bulb in a parallel connection is the same, as the voltage across each bulb is the same. So, the total power dissipated by the circuit is also the sum of the powers dissipated by the individual bulbs.

D. Voltage used by one of the light bulbs:
- Series connection: The voltage across each bulb in a series connection is a fraction of the total voltage supplied by the power source. So, the voltage used by one of the light bulbs would be less than the total voltage.
- Parallel connection: In a parallel connection, the voltage across each bulb is the same, equal to the total voltage supplied by the power source.

E. Resistance of one of the light bulbs:
- Series connection: The resistance of each bulb remains unchanged in a series connection.
- Parallel connection: The resistance of each bulb remains unchanged in a parallel connection.

By understanding the concepts of series and parallel connections and their effects on total resistance, total current, power dissipation, voltage across each bulb, and resistance of each bulb, we can determine the changes that occur in each scenario.