Lorena C.

asked • 05/25/16

A lamp is labeled 6.0V and 12W.

A.What current flows through the lamp when it is operating?
B. How much energy is supplied to the lamp in 1000 seconds?

Mark O.

Hi Lorena. By the way, if you are looking for a Math tutor, I am just a little north of you in Southlake.
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05/25/16

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Daniel G. answered • 05/25/16

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Part (A)
 
Use the equation P = IV where V is the voltage in Volts(V) , I is the current in amperes(A), and P is the power in Watts(W)
 
 
Part (B)
 
Watts are the measured Joules/seconds or J/s 
 
Joules measure energy, so  P = E/t, so to find the Energy just do E = P×t
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Mark O. answered • 05/25/16

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Hi Lorena,
 
A. The operating power of a lamp is given by
 
P = VI
 
So, solve for I: I = P/V = 12 W / 6.0V = 2A
 
 
B. Power is energy / time, or P = W/t where W is the energy. W is referred to as the work. Solve for the work:
 
W = Pt = (12 W)(1000 s) = 12,000 J
 
 
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Lorena C.

  1. What  the power supplied to a lamp that is operated by a battery having a 12V potential difference (aka.voltage) across it's terminals when the resistance  the lamp is 6.0Ω?
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05/25/16

Mark O.

Hi Lorena,
 
Here you know that in a resistive circuit where the battery has a voltage of 12 V and the resistance of the resistor is 6.0 Ω, you can use Ohm's law to find the current flowing in the circuit: V = IR. Solve for I = V/R = 12 V/ 6.0 Ω = 2 A.
 
Now that we know the current going through the lamp, we can use the formula for the power delivered by the lamp: P = VI = (12 V) (2 A) = 24 W
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05/26/16

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