65W bulbs connected in parallel (hopefully easy)

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In summary, the problem requires determining the number of 65-W light bulbs that can be connected in parallel across a potential difference of 85V before the total current in the circuit exceeds 2.1 A. To solve this, the power rating and current of each bulb are calculated, and it is determined that 2 bulbs can be connected without exceeding the maximum current allowed. The rounding of values is important in order to not exceed the maximum current.
  • #1
HyperSniper
39
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I know that this has to be an easy problem, but my teacher left us in December and we got stuck with an idiot who hasn't taught us anything since then...

Homework Statement


How many 65-W light bulbs can be connected in parallel across a potential difference of 85V before the total current in the circuit exceeds 2.1 A?

Homework Equations


[tex]\Sigma[/tex]1[tex]/[/tex]Req=1[tex]/R1[/tex]+1[tex]/R2[/tex]+1[tex]/R3[/tex]...
P=IV
V=IR

The Attempt at a Solution


I can't get an answer that makes any sense, but this is what I tried to do.

P=65-W
V=?
I=2.1A

P=IV
65=(2.1A)V
30.95V=V
R=14.738[tex]\Omega[/tex]

X= number of bulbs

[tex]\epsilon[/tex]= I((1/R)X)^-1
85V= (2.1A)(1/14[tex]\Omega[/tex])X)^-1
(14[tex]\Omega[/tex]/X)(2.1A)=85V
29.4V/X=85V
29.4V=(85V)X
.34588=X
 
Last edited:
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  • #2
I assume "before circuit exceeds 2.1A" is a typing mistake that means "before the total current out of the voltage source exceeds 2.1A".

Each bulb has a power rating P=VI, so it draws current I = P/V = calculate. That's one bulb. How many bulbs to reach the allowed maximum current?
 
Last edited:
  • #3
Opps. I'm sorry, I'll go fix it.

So does that mean it's just...

65W/85V=.76A

2.1A=(X)(.76A)
X=2.76

Rounding down not to exceed the maximum...

2 bulbs?
 
  • #4
It looks good to me. Just one suggestion for future problems that say "no not exceed" something, your rounding to 0.76 instead of saying 0.764 might have changed the answer. It's okay in this case.
 
Last edited:
  • #5
Thank you.
 

1. How do I connect 65W bulbs in parallel?

To connect 65W bulbs in parallel, you will need to first gather all of your materials, including the bulbs, wires, and a power source. Then, make sure to follow the correct wiring diagram, which involves connecting the positive terminals of each bulb to the positive terminal of the power source and the negative terminals of each bulb to the negative terminal of the power source.

2. What is the advantage of connecting 65W bulbs in parallel?

The advantage of connecting 65W bulbs in parallel is that each bulb will receive the same voltage and will operate independently. This means that if one bulb burns out, the others will still continue to work. Additionally, the brightness of each bulb will not be affected by the other bulbs in the circuit.

3. How many 65W bulbs can I connect in parallel?

The number of 65W bulbs that can be connected in parallel will depend on the power source and the maximum wattage it can handle. It is important to never exceed the maximum wattage of the power source to avoid overloading and potential damage. It is recommended to consult the power source's manual or an electrician for guidance.

4. Can I mix 65W bulbs with different wattages in a parallel connection?

No, it is not recommended to mix 65W bulbs with different wattages in a parallel connection. This is because bulbs with different wattages will have different resistances, which can cause unequal current flow and potentially damage the bulbs. It is best to only connect bulbs with the same wattage in parallel.

5. How do I determine the total wattage in a parallel connection of 65W bulbs?

To determine the total wattage in a parallel connection of 65W bulbs, you will need to add up the wattage of each individual bulb. For example, if you have 3 65W bulbs connected in parallel, the total wattage would be 195W (65W + 65W + 65W = 195W). This is helpful in determining the overall power consumption and ensuring that the power source can handle the load.

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