Physics MCQ, Oct/Nov 2005

[abcde]

AOA!
I don't seem to understand question 27 of this paper: http://www.xtremepapers.net/CIE/Cambrid ... 5_qp_1.pdf
Why is the answer D? :? :?:

 

[Nibz]

Oh come on! It's called a 'bacho vala' sawal! ( Childish as u call it in english)

 

[SalmanPakRocks]

Oh come on! It's called a 'bacho vala' sawal! ( Childish as u call it in english)

can you please explain it !! thanks in advance !!

 

[Nibz]

For current to flow, there must be a potential difference!
If earthed, electrons will start to flow, hence a potential difference will be created which will (sadly) blow that bird!

 

[SalmanPakRocks]

Ohh so the electrons aren't flowing when the bird is on wire ??

 

[Nibz]

Naaah... cuz the circuit is not complete!

 

[SalmanPakRocks]

thanks bro !!

 

[Nibz]

You are always welcome

 

[abcde]

Lol.. Bechara parinda.. (see I used Urdu, Nibz )

 

[scouserlfc]

Well yaar this was extremely easy i was also stumped when i tried on my first attempt LOL

 

[SalmanPakRocks]

well i also knew the answer of D but the problem was its explaination !! As this can be taken from example that people who repair the electric circuits and all that use a wooden table to stand on it as wood is an insulator and does not let the electrons pass so they don't get the electric shock !!

 

[Sehrish]

well i also knew the answer of D but the problem was its explaination !! As this can be taken from example that people who repair the electric circuits and all that use a wooden table to stand on it as wood is an insulator and does not let the electrons pass so they don't get the electric shock !!

That is because our body is a conductor whereas a bird's body is not a good conductor of electricity.

 

[scouserlfc]

No its not because birds are not good conductors,they are gud conductors but they are not conncted to the earth like us as @salmanpakrocks said that people who repair electric stuff use stools and if they dont they try to where some rubber slippers or electric gloves.

 

[SalmanPakRocks]

No its not because birds are not good conductors,they are gud conductors but they are not conncted to the earth like us as @salmanpakrocks said that people who repair electric stuff use stools and if they dont they try to where some rubber slippers or electric gloves.

Then it shouldn't be D !!

 

[abcde]

It is D. People who repair electric circuits use such insulators to prevent them from being earthed! The main thing is to avoid contact with the earth as that would complete the circuit, causing electrons to flow and produce an electric shock. @salmanpakrocks, please read the question again.

 

[SalmanPakRocks]

I m a little confused here !! but as @Sehrish said that Bird's body are not good conductor so why the answer will be D ?? as The insulator point is already given in the mcq's

 

[Sehrish]

Thankyou for correcting me here scouser.
I was right at bird's body is not good conductor (but partially) since it is a conductor but it is not better than the copper wires used in the power transmission lines where birds sit so there is no way for the electrons to detour thru the bird's body.

Like water flowing over a dam into a river, current surges through the bird (or person's) body if it is earthed(at 0 V) because current flows from higher potential to lower potential.

 

[SalmanPakRocks]

Thankyou for correcting me here scouser.
I was right at bird's body is not good conductor (but partially) since it is a conductor but it is not better than the copper wires used in the power transmission lines where birds sit so there is no way for the electrons to detour thru the bird's body.

Like water flowing over a dam into a river, current surges through the bird (or person's) body if it is earthed(at 0 V) because current flows from higher potential to lower potential.

Yeah !! I was kinda shocked to know that a brid's body is an insulator !!