Electrical Engineering - Voltage, Current and Resistance - Discussion

Discussion :: Voltage, Current and Resistance - General Questions (Q.No.4)

4. 

The minimum resistance value for a blue, gray, red, silver resistor is

[A]. 612
[B]. 6,120
[C]. 6,800
[D]. 6,460

Answer: Option B

Explanation:

Because of 10% tolerance(last color silver), this resistance may vary 10% of 6800.

Minimum resistance value = 6800 - 680 = 6120

Maximum resistance value = 6800 + 680 = 7480


Suraj said: (Dec 9, 2010)  
Answer is wrong.Correct answer is 6800

Mani said: (Jan 6, 2011)  
6800 right

Mihir said: (Jan 18, 2011)  
No the answer is 6120. they have asked for the minimum value. which must be 6800- 10% of 6800. (10% because the 4th color is silver which signifies 10% tolerance)

Prashant said: (Jan 20, 2011)  
B B R O Y G B V G W

Memorize this colors by the slogan "B B ROY Go to Bombay Via Gate Way of india" and remember the Capital Letters only.

Now Starting from first number them starting with 0.
So Black = 0
Brown= 1
Red = 2
Orange = 3
And so on.
Remember that there are four B in this equation and their order is Black Brown And Blue.


=> Now the first color of the Resistor is The decimal point.
In our CASE it is Blue so it is = 60(Decimal point)

=> Second one is the Unit point.
In our CASE it is Grey so it is = 08(Unit point)
Adding that two is now =68

=> Third on is the power of 10 and multiply it with the combination of decimal and unit point figure.
In our CASE it is Red so it is = 2 Hence it is equal to 10 rest to 2 = 10 ^ 2.
So now the Resistance will be 68 * 10 ^ 2 = 6800 Ohms

=> Now the Last color code is the tolerance hence it is to be introduced in Either in + or in - Formate with the percentage.
There are only 3 possible ways for tolerance.
Gold = +- 5%;
Silver = +- 10%
None = +- 20 %

In Our Case it is Silver so it is = +- 10 %

Finally we got the Resistance value for the given color code is
= 6800 +- 10 %

=> For minimum value substract the 10% of 6800 and or for the maximum value add the 10 % of 6800.

In our CASE it is Minimum so 68000 - 10 % of 68000
= 6800 - 0680
= 6120 ohms

Ans= B

Vipul said: (Jan 29, 2011)  
Option b is correct as we have to consider the tolerance.

Of silver that is +/-10%.

Aramuthan said: (Mar 16, 2011)  
Answer is wrong . The Answer is

Blue = 6
Grey = 8
Red = 2
So 6800 Ohms or 6.8k Ohms

Silver is tolerance

Kalaimani said: (Mar 30, 2011)  
Ans is "B", because question is minimum resistance value of given color code so it will be ans is "B"

Kalaimani said: (Mar 30, 2011)  
blue-6
grey-8
red-2
so value is 6800ohms
tolerance +-10%
therefore minimum resistance value is
6800/100*10=680

6800-680=6120ohms
so ans is "B"

Nibedita said: (Mar 31, 2011)  
B is right

Premshankar Behera said: (Aug 29, 2011)  
Due to tolerance of 10%, 6800+/-10/100*6800 = 6000 to7600. So according to above mentioned answer 6120 is the lowest value.

Hence answer is 6120.

Ranjeet Kr Singh said: (Nov 15, 2011)  
As per colour code
blue grey red silver
6 8 * 10^2 - 10%
so 6800-(6800*10%)
= 6800-680 = 6120 ans.

Veena said: (Dec 24, 2011)  
Yeah B s correct. As silver has 10% tolerance.

Sandy said: (Apr 10, 2012)  
6120 is the correct answer due to the tolerance of the 10% (silver colour) in the resistance value thus as per general calculation 6800.

But 10% of 6800 is 680 thus answer may.

6120 or 7480, here the option available is 6120 thus the answer is 6120.

Rani said: (Aug 31, 2012)  
YES ANS B, & thanks to PRASHANT

Haneef said: (Dec 23, 2012)  
Blue, gray, red, silver.

68*10^2 (-10%).

Tolerance is minimum so substrata if max add.

So, (6800/100) *10=680.

6800-680=6120.

Amit said: (Nov 25, 2013)  
What is the current of an 208V, 111kW three-phase load with cosFI=0.99 ?

Nikhil Bhargava said: (Feb 3, 2014)  
Blue-grey-red-silver,

68*10^2 (-10% tolerance).
6800-(6800*10%).
= 6800 - 680.
= 6120.

Answer is B.

Mithlesh Pandey said: (Mar 28, 2014)  
Ya this question all right.

The answer is = 6120 is to be correct.

Prince Dixit said: (Oct 18, 2016)  
I agree that, 6120 is the right answer.

Bhadri said: (Nov 24, 2016)  
I agree with the given answer, i.e. option b.

Arpit Darji said: (Mar 14, 2017)  
Thanks for all the given explanation.

Shashank said: (Aug 10, 2017)  
What will be the answer if they not ask silver?

Ejja Rakesh said: (Feb 20, 2020)  
Thanks, @Prashanth bro for your deep explanation it's better than any other tutor.

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