A steam iron draws 6.5 A when connected to a potential difference of 120 V.
(a) What is the power rating of this iron?
1 W
(b) How many joules of energy are produced in 20.0 min?
2 J
(c) How much does it cost to run the iron for 20.0 min at $0.014/kW·h?
$ 3
P =I•U = 6.5•120 =780 W
E = P•t =780•20•60 =9.36•10^5 J.
1 J = 2.78⋅10^ -7 kWh
9.36•10^5 J =0.26 kWt.
0.26 kWt •$0.014/kW•h = $0.00364
To find the power rating of the steam iron, we can use the formula:
Power (P) = Current (I) x Potential Difference (V)
Given that the current is 6.5 A and the potential difference is 120 V, we can substitute these values into the formula to find the power rating:
P = 6.5 A x 120 V
P = 780 W
So, the power rating of the steam iron is 780 W.
To find the energy produced in joules (J) in 20.0 minutes, we need to calculate the total energy consumed:
Energy (E) = Power (P) x Time (t)
Given that the time is 20.0 minutes (which can be converted to seconds by multiplying by 60), we can substitute these values into the equation to find the energy in joules:
E = 780 W x (20.0 min x 60 s/min)
E = 936,000 J
So, 936,000 joules of energy are produced in 20.0 minutes.
To find the cost of running the iron for 20.0 minutes at $0.014/kW·h, we need to calculate the total kilowatt-hours (kW·h) consumed:
Energy (E) = Power (P) x Time (t)
Given that the time is 20.0 minutes (which can be converted to hours by dividing by 60), we can substitute these values into the equation to find the energy in kilowatt-hours:
E = 780 W x (20.0 min / 60 min/h)
E = 260 Wh = 0.26 kWh
Next, we can calculate the cost by multiplying the energy in kilowatt-hours by the cost per kilowatt-hour:
Cost = Energy (E) x Cost per kilowatt-hour
Cost = 0.26 kWh x $0.014/kWh
Cost = $0.00364
So, it cost $0.00364 to run the iron for 20.0 minutes at a rate of $0.014/kW·h.