Calculate the resistance, then find the current at the new voltage

In summary, resistance can be calculated using the formula R = V/I, where R is measured in ohms, V is measured in volts, and I is measured in amperes. The current at a new voltage can be found using the formula I = V/R. There is an inverse relationship between resistance and current, meaning that as resistance increases, current decreases and vice versa. Resistance and current can both change with a change in voltage, with current potentially increasing or decreasing depending on the resistance.
  • #1
srhly
17
0
A 78.9 W, 107.3 V light bulb is plugged into a 59.2 V outlet. If energy costs 4.9 cents/kW*h, how much does it cost per month (30 days) to leave the light bulb turned on? Answer in units of cents.

This is what I did:

(78.9W/107.3V)(59.2V)(24hours)(30days)(4.9cents/kW*h)(1kW/1000W)

I got 153.58 cents. I know the answer is incorrect, but where did I go wrong?
 
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  • #2
P=VI
V=IR

Calculate the resistance, then find the current at the new voltage. Then use conversion factors to get your price.
 
  • #3
Thanks, that helped!
 

1. How do you calculate resistance?

The formula for calculating resistance is R = V/I, where R is the resistance in ohms, V is the voltage in volts, and I is the current in amperes.

2. What units are used to measure resistance?

Resistance is measured in units of ohms (Ω).

3. How do you find the current at a new voltage?

To find the current at a new voltage, you can use the formula I = V/R, where I is the current in amperes, V is the voltage in volts, and R is the resistance in ohms.

4. What is the relationship between resistance and current?

There is an inverse relationship between resistance and current. This means that as resistance increases, current decreases, and vice versa.

5. Can resistance and current change with a change in voltage?

Yes, resistance and current can both change with a change in voltage. As voltage increases, current may increase or decrease depending on the resistance, and as voltage decreases, current may also increase or decrease.

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