Electronics - Series-Parallel Circuits - Discussion


If four 10 komega.gif resistors are in series with a single 20 komega.gif resistor and one of the parallel resistors shorts, the voltage across the other parallel resistors ________.

[A]. increases
[B]. decreases
[C]. remains the same
[D]. drops to zero

Answer: Option B


No answer description available for this question.

Sanjeet Singh said: (Aug 19, 2011)  
The question is not clear. Which parallel connection is it talking about. Please explain me.

Neelaji said: (Feb 8, 2012)  
As per the circuit analysis most of the current is passed through the short circuit.In question how much voltage drop across parallel resistors.
ANSWER IS INCREASES because according to ohms law v is proportional to I

Rm Bahuguna said: (Jun 4, 2012)  
Because all the four 10 k ohm resisters are in parallel so voltage across other three resister will drop to zero, if get shorted.

Afash said: (Jan 10, 2014)  
Voltage is same in parallel connection. So how it is possible that voltage be decreased. Here some twist in the Q.

Tim J said: (Mar 1, 2015)  
Here is the answer. If one of the 4 resistors in parallel shorts, the resistance in the entire circuit increases. Whether or not 20K ohm is present or not it would still increase. Here is the proof:

1/10+1/10+1/10+1/10 or 1/10*4 = 400*10-3 (x-1) is reciprocal = 2.5 ohms.

1/10+1/10+1/10 or 1/10*3 = 300 E-3 reciprocal = 3.33 ohms!

Tim J said: (Mar 1, 2015)  
Here again, I almost forgot: As related to my last response.

I*R = V. So let's just use a random current value for the proof of say 6mA.

= (1/10*4) = 2.5K (1/10*3) = 3.33K.

= 6mA*2.5Kohm = 15 volts.

6mA*3.3Kohm = 19.8 volts, so I believe the answer may be that current decreases when one of the resistors burns out.

If the same voltage were applied to the circuit then current would definitely decrease. You can look at the question either way but the result is the same.

V = I*R.

Santosh said: (Jun 14, 2016)  
From this question, if one of the resistor in parallel connection shorted means over all resistance of parallel is zero show from the ohm's law V = I*R.
If R decreases voltage also decresed.

Anil Kumar said: (Mar 31, 2017)  
If one Resistor is short in parallel connection means here Resistance in parallel circuit is zero. It means voltage drop in parallel circuit is zero.

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