Electronics - Series Circuits - Discussion

Answer is option B.

Consider the correct combination is (+- +- +-)
Since they did not mention which battery we are putting backwards,
We can assume three possible combinations i.e.

1 (+- -+ +-) here 1st two batteries nullify each other and acts as short circuit so light will work only by the 3rd battery

2 (-+ +- +-) here also 1st two batteries nullify each other and acts as short circuit so light will work only by the 3rd battery

3 (+- +- -+) here 2nd and 3rd batteries nullify each other and acts as short circuit so light will work only by the 1st battery

So in all the three combinations the light will work only by one battery so the light will be dimmer than normal

Yes. Answer is B.

Because see below.

(+-) (+-) (+-).

If we put 3 of the batteries in this polarity then voltage will be added.

But as given that one is inverted so direction will be:

(+-) (+-) (-+) so opposite polarity will reduce the voltage to zero. So ultimately voltage will be reduced and battery will give dimmer light.

By doing so.

Final applied voltage to torch is 1.5 Volt.
When it is inserted in correct manner it should be 4.5 Volts.

So theoretically, 1.5 Voltage is provided to torch so it will be slightly lighting is answer.

Total voltage= +1.5v + 1.5v - 1.5v = +1.5v

I think the light will be dimmer than normal because

3 batteries = ( + - + - + -)
But here one is inverted so

3 batteries = ( + - + - - + )
So the power will be from 1st battery itself i.e., the power will be from only one 1.5v.

So the ans is B.

When inserting batteries into any device one battery direction will be opposite to each other, right?

Then in inserting 3 batteries one will be in opposite to the other two na.

So what is wrong? I can't understand. Please explain.

As per the condition of series circuit, voltage in series are added. Here three batteries each 1.5V is connected with one reverse direction so +1.5,+1.5,-1.5 . In final result the output voltage is +1.5v so the light surly dimmer.

Brothers this is rubbish. Of Course the torch would be off as by changing polarities doesn't means battery is shorted for a circuit to complete the path. Also I have tested it practically it doesn't work.

ITs simple...
3 bateries are there... if the middle one is backwards it act as wire between 1st and 3rd.. so dimmer than normal...
in other case:battery backwards in 1st or 3rd the light will be off...

If the question means that one of the batteries in put inverted into the flashlight then answer should be "c". ie, flashlight will not work in this condition.

For working of torch to glow there is requirement both polarities (+) (-) are needed so torch will remain off as both end polarity is same.