Electrical Engineering - Series-Parallel Circuits - Discussion

Discussion :: Series-Parallel Circuits - General Questions (Q.No.7)


A certain voltage divider consists of three 1 k resistors in series. Which of the following load resistors will have the least effect on the output voltage?

[A]. 1 M
[B]. 100 k
[C]. 1 k
[D]. 330

Answer: Option A


No answer description available for this question.

Panneer said: (Jul 6, 2011)  
Please explan to me this answer.

Siva said: (Jul 7, 2011)  
Output voltage = r1.r2/r1+r2 = 1.1/1+1 = 2/2 = 1 m ohms

Ganeshbabu said: (Jul 25, 2011)  

How it is possible 1.1/1+1 = 2/2 =1 ?

Anand said: (Jul 27, 2011)  
Can anybody explain briefly about the answer?

Suyash Singh Panwar said: (Jul 30, 2011)  
Three 1 ohm resistor in series then total resistance is 3 ohm
knom we connect 1 Mohm resistor then appling voltage divider rule .

Vout= R2*Vin/R1+R2 = 1*1000 kHZ/1000+3 = 0.997
the 1Mohm resistor is least effect on the output.

A.Harish said: (Aug 23, 2011)  
How it is possible. R1+R2=1000+3.

Saurabh K. Chhaya said: (Oct 13, 2011)  
1K because all resisters are same value so ans is 'C'

Rohit said: (Jan 6, 2012)  
According to ohm's law: V=IR & I=V/R; so that output volt. is most affected when I is high & I is high when R is low, But output volt. is least affected when I is low so that R is high. R=1M

Krishna said: (May 7, 2012)  

Harpreet Singh said: (May 17, 2012)  
When we increase output resistance highly. Then effect on output voltage is also high.
We have 1MOhm high value resistace which effects to output voltage high.
Hence Answer is 1 M Ohm.

V.P.Vignesh said: (Jun 27, 2013)  
Can anybody explain difference between least effect and most effect.

V.P.Vignesh said: (Jun 27, 2013)  
Least effect means voltage will lesson than the previous voltage or greater than the previous voltage.

Pawan Kumar said: (Jan 9, 2014)  
1*1/1+1 = 2/2 how can possible & same R1*R2=1000*3 possible.

Prahlad said: (Feb 11, 2014)  

I inversely proportional to R

And power loss = I^2R.

When more R, than less I.

And less I than less power loss.


So simple high are than OUTPUT VOLTAGE is high.

Narasimha said: (Jun 21, 2014)  
Here voltage divider having the low values of resistors. These can allow the some what of fluctuations when the input voltage is get changes by means when we increase input voltage we will get effected output voltage but we are using high range resistor we get least effected output voltage. That means high range resistor strongly opposes the changes in voltage. Here the change will be the effect.

Vipin Kumar said: (Aug 18, 2014)  
As we connect one of the series resistance with load in parallel and we know that parallel of two things results in lesser than lesser thing, but larger the value of load resistance parallel will be nearer to lower resistance. So will affect v less so see largest resistance.

Anu said: (Sep 2, 2014)  
By ohm's law V=IR.


Hence less will be resistance more is the current flowing so more voltage dropped and low resistance will more effect on output voltages.

Smita said: (Sep 18, 2014)  
There is all ready total resistance is 3 kilo-ohm.
If resistance less then least effect on source voltage.

So I think 330 ohm is small resistance so answer is this one.

Husain said: (Oct 24, 2014)  
Here we got R2 = 3kohm = 3000ohm.

Lets take minimum resistor R1 = 1kohm = 1000ohm.

Vout = (R2/R1+R2) Vin.

= (3000/1000+3000)Vin.

= 0.75Vin.

So Vout/Vin = 0.75.

Now for max resistor R1 = 1Mohm = 1000000ohm.

Vout = (R2/R1+R2)Vin.

= (3000/1000000+3000)Vin.

= 0.003Vin.

So Vout/Vin = 0.003.

Sony Jony said: (Feb 28, 2015)  
First of all least effect is not big difference in voltage. I equals V/R resistance increases current decreases if we are using 330 as answer it will get big current and voltage drop will be big but question is least effect. So biggest value is answer so current will be less so voltage drop will be less.

Waqas Khalil said: (May 21, 2015)  
R1= 3(1k ohm) = 3k ohm.

Vout = (R2/(R1+R2))Vin.

Lets take minimum resistor R2 = 330 ohm.

Vout = (R2/(R1+R2))Vin.
Vout = (330/3330)Vin.
Vout = 0.099 Vin.

Lets take maximum resistor R2 = 1M ohm.

Vout = (R2/(R1+R2))Vin.
Vout = (1M/1003000)Vin.
Vout = 0.997 Vin.

Here you can observe, bigger the value of R2, smaller the effect on Vout. So, the answer is 1M ohm.

Amith said: (Jun 5, 2015)  
The Circuit has three 1 K ohms in series & load resistor also.

Question is which of the following load resistors will have the least effect on the output voltage?

330 ohms will have the least effect on voltage across 1 K ohms.

Kkk said: (Jun 19, 2015)  
The question is when you connect which value of the following resistor the value of output voltage doesn't alter a lot.

Out of the four 1 M is the high value of load resistance which is equal to open circuit when compared to other.

Soumen said: (Aug 20, 2015)  

How it's possible 1.1/(1+1) = 1?

Jagadesh said: (Feb 23, 2016)  
As the question is that among the options which has least effect on output voltage. As all option except 1M is less than or equal to 1K so the output of voltage divider has the effect on other 3 loads except 1M because for a high value load resistance the current for specified voltage will be low as compared to low load. So 1M will be effected least.

Danyal said: (Mar 6, 2016)  
Voltage drop is directly related to resistance.

Higher the resistance higher will be the voltage drop.

Voltage drops across internal resistances of the source, across conductors, across contacts, and across connectors are undesired; as supplied energy is lost (i.e. dissipated).

Voltage drops across loads are desired; as supplied energy performs useful work.

Hence in the above question the supplied energy will be put to maximum use when the value of load resistance is maximum.

As the question is asked for load resistance the answer will be 1M ohm.

If the question would have been for internal resistance then the answer would have been 330 ohm.

Dhanasekar said: (Mar 30, 2016)  
Please give me the correct solution for this one.

Sandeep K J said: (Apr 26, 2016)  
The effect of load on terminal voltage depends on load resistance, if the load resistance is less than current drawn by the load will be more hence terminal voltage drop is more.

Hence, most resistance load will have less effect on voltage.

Sam said: (May 10, 2016)  
As per Loss formulae: I^2.R & Ohm's Law: I inversely proportional to R.

More Resistance higher will be the loss.

1Mohm is the huge value of resistance.

Definitely, the output voltage is very less.

Hence, the answer for least effect is 300 ohm.

Otherwise, Data is insufficient.

Pawan Dhiman said: (Jun 19, 2016)  
How possible total resistance in series is 3 ohm? while every resistance has a value of 1 Kohm.

Puja said: (Jan 11, 2017)  
Please, someone explain me briefly. I don't understand still.

Rahul K said: (Jun 20, 2017)  
By ohms law v=ir.

I.e. I is inversely proportional to r.
Hence, when r is more than I is less but I is directly proportional to v hence v is also less. R=1Mohm is more in above options.

Sanju said: (Jul 25, 2017)  
Can anyone explain this?

Saranya said: (Aug 25, 2017)  
Somebody explain this clearly? I can't understand.

Mahes said: (Jan 26, 2018)  
The circuit is connected in series, so current is the same through each resistor is same....though all resistant are having the same value. Each resister will consume same power (i.e. I^2R) and the voltage drop across each resistor is same(i.e. v=IR).

Ayo said: (May 14, 2018)  
Use the rule of voltmeter impact on measured circuit.

Mark E. said: (May 30, 2018)  
The question is pertaining to Voltage Divider, hence: V(output) = V(input) * (R1 / (R1 + R2))
Since the question is the LEAST effect of the Output Voltage we can then assume any value for V(input) in the example below I used 5 Volts, R1 or R (load) is connected parallel to the 3 series resistor because that is how voltage divider works and example would be like this.

V (out) = 5V * (1M ohms / (3K ohms + 1M ohms) = the answer would be appromately equal to 5, since the output and input are almost of equal value then R (load) which is 1 M ohms has the LEAST effect on the circuit.

Manik said: (Sep 8, 2018)  
If R is max then current I will be less thus least effect on the circuit.

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