Consider an ordinary 100w incandescent light bulb and a led light bulb that produces the same amount of light, but consumes 20w of electricity. assuming the values for purchase price and lifetime for each bulb, and a cost of electricity as given below, compute the number of hours of usage required for the led light bulb to become more cost-effective than the incandescent bulb for each case below. if the crossover in cost occurs because a new bulb must be purchased, you may take the number of hours to be equal to the time at which the bulb must be purchased. note: one year of moderate usage corresponds to ~1000 hours.

Assuming the the values for purchase price and lifetime for each bulb, and a cost of electricity are:

Incandescent Bulb

Power:100W

Purchase Price: $1.50

Lifetime:

Electricity cost: $0.10/kWh

LED Bulb

Power:20W

Purchase Price: $40

Lifetime:

Electricity cost: $0.10/kWh

Let's begin with the calculations:

The electric energy used for a bulb is:

(1)

Where is the electric power and the time the bulb is used.

And the operating cost is:

(2)

Where is the Electricity cost in units of

For the Incandescent Bulb:

(3)

(4) This is the electric energy used

Calculating the cost:

(5)

(6)

(7) This is the electricity cost for incandescent light bulb for 1000 hours

For the LED Bulb:

(8)

(9) This is the electric energy used by the LED bulb

Calculating the cost:

(10)

(11)

(12) This is the electricity cost for LED bulb for 25000 hours

As we can see the use of LED bulb for 25 years (25000 h) is $50, this means in 1 year the cost would be $2.

On the other hand, the use of Incandescent bulb for 1 year (1000 h) is $10.

This means using the LED bulb will result more cost-effective than the Incandescent bulb, although the initial investment is high.

the independent variable, the one that is intentionally manipulated, is whether or not the car hits the barrier.

the dependent variable, the one that you measure the response in, is the distance that the washers travel.

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27