A 4-W night-light is plugged into a 120-V circuit and operates continuously for 1 year. Find the following: (a) the current it draws, (b) the resistance of its filament, (c) the energy consumed in a year. (d) Then show that for a utility rate of 15¢/kWh the cost for a year’s operation is $5.25.

Solution 7P Given, Power P = 4-W Potential V = 120- V (a) Therefore, current I = P/ V I = 4/120 A I = 1/30 A (b) Resistance R = V /I R = 120/(1/30) Ohm R = 3600 Ohm (c) Time = 1 year Time = 365 days Time = 365 × 24 h Energy = Power × Time...