Relationship between voltage, power and current

  • #1
Misplaced homework thread moved here by moderator, hence no template.
Hy,
If we double the voltage than what will be double
A. power
B. Current
C. Resistance
D. Both a & b
 

Answers and Replies

  • #2
Svein
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As usual: It depends. You have not specified the context. A drawing would help.
 
  • #3
As usual: It depends. You have not specified the context. A drawing would help.
When we double the voltage in a simple electric circuit, we double the
A. Current
B. Power
C. Resistance
D. Both current and power
 
  • #4
davenn
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When we double the voltage in a simple electric circuit, we double the

you still haven't specified the circuit setup
until you fix (state) a couple of the variables, your Q cannot be answered

Dave
 
  • #5
you still haven't specified the circuit setup
until you fix (state) a couple of the variables, your Q cannot be answered

Dave
Actually problem is that
This question is on the text book which is recommended by government.
 
  • #6
Actually problem is that
This question is on the text book which is recommended by government.
So there is not show any circuit
 
  • #7
davenn
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So there is not show any circuit

so, so let me provide you with a circuit ......

upload_2017-1-23_18-22-49.png


a nice simple one, a battery and a resistor

do you know Ohm's Law ? ....
 
  • #9
davenn
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Yes I know

OK, good

so you have 10V across a 10 Ohm resistor ...
what is the current flowing in that circuit ?

show me your working :smile:
 
  • #10
OK, good

so you have 10V across a 10 Ohm resistor ...
what is the current flowing in that circuit ?

show me your working :smile:
1 A
 
  • #11
davenn
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1 A

correct

so if you now increase the voltage to 20 V, what is the current in the circuit ?
 
  • #12
correct

so if you now increase the voltage to 20 V, what is the current in the circuit ?
2 A
 
  • #13
davenn
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  • #14
correct [emoji2]
so next, what is the formula for finding power ?
P = I V
P= I (2) R
P = V (2) / R
 
  • #15
davenn
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P = I V
P= I (2) R
P = V (2) / R

Yup
for ease we can use your first choice P = I x V

work out the two power levels for the examples we have just done

then answer your original Q .....

Hy,
If we double the voltage than what will be double
A. power
B. Current
C. Resistance
D. Both a & b




Dave
 
  • #16
Yup
for ease we can use your first choice P = I x V

work out the two power levels for the examples we have just done

then answer your original Q .....






Dave
Mean D option is correct
 
  • #17
davenn
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Mean D option is correct

yes, well done :smile:

wasn't too difficult to work out, huh :wink:
.

Dave
 
  • #18
yes, well done [emoji2]
wasn't too difficult to work out, huh :wink:
.

Dave
Thanks
But
Is this answer corrected. If current is double
P = 2 I * 2 V
 
  • #19
davenn
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Is this answer corrected. If current is double

unlike voltage or resistance, current cannot just change
current is a RESULT of a given voltage across a given resistance
That is, current can ONLY change IF the voltage OR the resistance changes

And the power, in Watts, dissipated in a circuit, in our circuits above ( in the resistor)
is always related to the voltage across the resistance divided by the resistance

so for a fixed resistance, if the voltage is doubled, then the current is doubled and therefore so is the power dissipated


Dave
 
  • #20
unlike voltage or resistance, current cannot just change
current is a RESULT of a given voltage across a given resistance
That is, current can ONLY change IF the voltage OR the resistance changes

And the power, in Watts, dissipated in a circuit, in our circuits above ( in the resistor)
is always related to the voltage across the resistance divided by the resistance

so for a fixed resistance, if the voltage is doubled, then the current is doubled and therefore so is the power dissipated


Dave
Power dissipated mean?
 
  • #22
davenn
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Power dissipated mean?

power lost, radiated, used up <---- take your pick, all the same :smile:
 
  • #24
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I moved it to homework, where it better fits and can be found by others with similar questions.
 
  • #25
gneill
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Mean D option is correct
Check again the amount by which current and power changed. They don't change by the same factor.
 
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