Calculate the individual voltage, current and power in series and para

  • Thread starter nickbb12
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Homework Statement:
A set of 16 party lights were purchased for the patio, 2x of 8 sets of bulbs are in parallel with each other, so if i disconnect one bulb, only half of the lights will go out. When all bulbs are functional they draw 3.2Amps from the 24.0V transformer. I need to determine the voltage across each globe, the current through each globe, the power consumed by each globe and finally, if we had a power board with a circuit breaker rated to flip at 10A, how many sets of lights could I operate before flipping the circuit breaker? Thanks :)
Relevant Equations:
V = IR
P = IV
V = 24V
I = 3.2A
16 globes (2x 8 in parallel) (8 globes in series)
To determine the voltage I did voltage/number of globes:
24/16 = 1.5V per globe
- Not sure if this is correct or not

To determine current, I figured out using resistance formulas that the resistance for each set of 8 globes is 15 ohms
R = V/I
24/3.2 = 7.5 ohms total resistance
7.5-1 = 2 * 15-1
Each set of 8 has resistance of 15 ohms.

therefore each globe has an individual resistance of 1.875 ohms, I then used I = V/R to get 0.8A per globe.
- Not sure if this is correct or not

To solve power I simply did P = IV,
1.5 x 0.8 = 1.2W
- Again, not sure if this is correct

The last one I'm stumped, no idea how I could figure it out.
Thanks in advance for people who reply :)
 

Answers and Replies

  • #2
haruspex
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To determine the voltage I did voltage/number of globes:
24/16 = 1.5V per globe
- Not sure if this is correct or not
What answer would you have given if all 16 had been in series?
Should it make a difference that it consists of two parallel strings of 8 instead?

Draw a diagram of the circuit, marking the ends with voltages (0 at one end, 24 at the other, say).
If the voltage drop across each bulb is v, what should the difference at the ends be?
 

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