You have an LED bulb that uses 4 watts of power and gives an output of 170 lumens. The operating voltage is 120 volts. Using this data, find the following.
1. What is the current that the LED bulb uses?
Ans. 0.03 ampere
2. What is the effective resistance of this bulb?
I'm not sure what they mean by effective resistance, but I found the resistance to be 4000 ohms.
3. How much does it cost to use this bulb for 2 hours at a rate of $0.12/kWh?
Ans. $0.00144
1. agree Power = Voltage* current
so i = P/V = 4/120 = .0333 amps
2. R = V/i = V*2/P = 3600 ohms
3. Power * time = energy used
= 4 * 2 = 8 watt hours = .008 kwhr
.008*.12 = .00096 dollars
To find the answers to the given questions, we can use the formulas and relationships between power, voltage, current, resistance, and energy consumption. Let's break down the steps for each question:
1. What is the current that the LED bulb uses?
The formula to calculate current is:
Current (I) = Power (P) / Voltage (V)
Substituting the given values:
P = 4 watts
V = 120 volts
I = 4 watts / 120 volts
I = 0.0333 amperes (rounded to 4 decimal places)
Therefore, the LED bulb uses a current of approximately 0.0333 amperes.
2. What is the effective resistance of this bulb?
The effective resistance can be calculated using Ohm's Law:
Resistance (R) = Voltage (V) / Current (I)
Substituting the given values:
V = 120 volts
I = 0.0333 amperes
R = 120 volts / 0.0333 amperes
R = 3603.60 ohms (rounded to 2 decimal places)
Therefore, the effective resistance of the LED bulb is approximately 3603.60 ohms.
3. How much does it cost to use this bulb for 2 hours at a rate of $0.12/kWh?
To calculate the cost of energy consumption, we need to determine the energy consumed by the bulb (in kilowatt-hours) and multiply it by the rate.
Energy consumed (E) = Power (P) x Time (T)
Converting the time to hours:
T = 2 hours
E = 4 watts x 2 hours
E = 8 watt-hours
Converting watt-hours to kilowatt-hours:
E = 8 watt-hours / 1000
E = 0.008 kilowatt-hours
Multiplying by the rate:
Cost = Energy consumed (E) x Rate
Substituting the given values:
E = 0.008 kilowatt-hours
Rate = $0.12/kWh
Cost = 0.008 kilowatt-hours x $0.12/kWh
Cost = $0.00096 (rounded to 5 decimal places)
Therefore, the cost to use this bulb for 2 hours at a rate of $0.12/kWh is approximately $0.00096.