One lightbulb is marked \"25 W 150 V\" and another \"100 W 150 V\"; this means t

Question

One lightbulb is marked "25 W 150 V" and another "100 W 150 V"; this means that each bulb has its respective power delivered to it when plugged into a constant 150 V potential difference.

The charge remains unchanged in every way. The charge increases.     The charge is put out at a lower potential. The charge decreases.

(c) How long does it take for 1.00 J to pass through the dim bulb?
?t = 5 s
By what mechanisms does this energy enter and exit the bulb?

The bulb takes in energy by electrical transmission and puts out a greater amount by heat and light. The bulb takes in energy by electrical transmission and puts out the same amount by electrical transmission.     The bulb takes in energy by electrical transmission and puts out a lesser amount by heat and light. The bulb takes in energy by electrical transmission and puts out the same amount of energy by heat and light.

(d) Find how much it costs to run the dim bulb continuously for 30.0 days, if the electric company sells its product at $0.0700 per kWh.
Cost = $ 7
What product does the electric company sell?
8
What is the price for one SI unit of this quantity?
Cost per unit: 9 dollars /10---Select---WattsJoulekWhOhm

One lightbulb is marked 25 W 150 V and another 100 W 150 V; this means that each bulb has its respective power delivered to it when plugged into a constant 150 V potential difference. (a) Find the resistance of each bulb. 25 W 150 V: 1 Ohm 100 W 150 V: 2 Ohm (b) How long does it take for 1.00 C to pass through the dim bulb? ?t = 3 s Is the charge different in any way upon its exit from the bulb versus its entry? The charge remains unchanged in every way. The charge increases. The charge is put out at a lower potential. The charge decreases. (c) How long does it take for 1.00 J to pass through the dim bulb? ?t = 5 s By what mechanisms does this energy enter and exit the bulb? The bulb takes in energy by electrical transmission and puts out a greater amount by heat and light. The bulb takes in energy by electrical transmission and puts out the same amount by electrical transmission. The bulb takes in energy by electrical transmission and puts out a lesser amount by heat and light. The bulb takes in energy by electrical transmission and puts out the same amount of energy by heat and light. (d) Find how much it costs to run the dim bulb continuously for 30.0 days, if the electric company sells its product at $0.0700 per kWh. Cost = $ 7 What product does the electric company sell? 8 What is the price for one SI unit of this quantity? Cost per unit: 9 dollars /10---Select---WattsJoulekWhOhm

Explanation / Answer

(a)
   we use the equation from the theory givenby   
   P = (?V)2 / R
   the resistance of each bulb will be
   Rdim = (?V)2 /Pdim
           = (150V)2 / 25.0 W
           =900 ?
   Rbright = (?V)2 /Pbright
           = (150V)2 / 100 W
           =225 ?
(b)
   the current in the dim will be
   I = Pdim / ?V
     = 25.0 W / 150 V
     = 0.1666 amps
   so the time for 1.00 C to pass through the bulb willbe
   ?t = ?Q / I
        = 6 s
   when the charge emerges from the bulb it has lowPE
(c)
   the time for the dim bulb to dissipate 1.00 J ofenergy is
   ?t = ?E / Pdim
        = 1/25 =0.04s
(d)
   in 30 days the energy used by the dim bulb willbe   
   E = Pdim t
      = (25.0 W) (30 d) (24 hr /d)
      = 18 kW hr
   find unit cost

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