A steam iron draws 8.0 A when connected to a potential difference of 125 V.
a) What is the power rating of this iron?
Answer in units of W.
b) How much energy is produced in 55.0 min?
Answer in units of J.
c) How much does it cost to run the iron for
55.0 min at $0.010/kW·h?
Answer in units of dollars.

A. 1000 W

B. 3.3×10⁶ J

C. $ 0.00917

Explanation:

A. Determination of the power rating of the iron.

Potential difference (V) = 125 V

Current (I) = 8 A

Power (P) =?

P = IV

P = 125 × 8

P = 1000 W

B. Determination of the energy.

We'll begin by converting 55 mins to seconds. This can be obtained as follow:

1 min = 60 s

Therefore,

55 mins = 55 × 60

55 mins = 3300 s

Finally, we shall determine the energy. This can be obtained as follow:

Power (P) = 1000 W

Time (t) = 3300 s

Energy (E) =?

E = Pt

E = 1000 × 3300

E = 3300000 J = 3.3×10⁶ J

C. Determination of the cost of operation.

We'll begin by converting 3.3×10⁶ J to KWh. This can be obtained as follow:

1 J = 2.778×10¯⁷ KWh

Therefore,

3.3×10⁶ J = 3.3×10⁶ × 2.778×10¯⁷

3.3×10⁶ J = 0.917 KWh

Finally, we shall determine the cost of operation. This can be obtained as follow:

Energy (E) = 0.917 KWh

Cost per KWh (Cₚₖ) = $ 0.01

Cost of operation =?

Cost of operation = E × Cₚₖ

Cost of operation = 0.917 × 0.01

Cost of operation = $ 0.00917

c)as speed changes, wavelength and frequency change.

everything changes!

0.11 m/s and 0.28 m/s should be correct