SOLUTION: for a resistor in a direct circuit that does not vary its resistance, the power that a resistor must dissipate is directly proportional tp the square of the voltage across the resi

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Question 907585: for a resistor in a direct circuit that does not vary its resistance, the power that a resistor must dissipate is directly proportional tp the square of the voltage across the resistor. the resistor must dissipate 1/16 watt power when the voltage across the resistor is 14 volts. find the power the resistor must dissipate when the voltage across it is 42 volts
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
For a resistor in a direct circuit that does not vary its resistance, the power that a resistor must dissipate is directly proportional to the square of the voltage across the resistor.
The resistor must dissipate 1/16 watt power when the voltage across the resistor is 14 volts.
Find the power the resistor must dissipate when the voltage across it is 42 volts.
:
The power equation for this problem
P = E%5E2%2FR where E = the voltage, R = resistance in ohms, P in watts
Find the resistance
1%2F16 = 14%5E2%2FR
1%2F16R = 196
multiply both sides by 16
R = 3136 ohms
:
When voltage is 42 volts
P = 42%5E2%2F3136
P = 1764%2F33136
P = .5625 watts (9%2F16) Watts
:
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We can note here that when you triple the voltage, you increase the power by 3^2