Physics Paper 2

[maybeitwasnoone]

June 2006
Question 6 c
7 a and b

I do know the answers, I just need the explanation. Thanks

 

[msk]

7 a) lamp c is short because see when lampc c is short that means all the curent passes thorugh c and the b is out of equation...( current has the property to pass thorugh where it has the least hinderance) so it pass through c and a...since c is hsort the ohm-meter will only show the reading of a...i.e 15 ohm

b) ohm-meter supplies very less current so shortage of lamp is not a problem....but power supply is there it provides a voltage which can damge the powr supply because lamp c is hsort.....ms says lamp A is short that is wrong...i ahve discused this question with my teacher

 

[maybeitwasnoone]

Thanks msk, Didnt get the bit about a) though :S

Question 6 anyone?

 

[msk]

see short means there is very less resitance and almost all the current will pass through it......in the table given in the question the last column in which switch S2 and S3 are closed that means current will pass through A B and C.....but C is shorted so all the current passes thorugh C and none out of B....so ohm-metre will give reading of A+C ....since C is shorted reading displayed is only of A i.e 15 ohm.... hope u get it now

 

[hassam]

well msk.....when power supply is connected it will damage other bulbs or blow out fuse or melt wire etc....b/c it ll cause a very large current to flow which will flaw if resistance is very low...so if A is not shorted than connecting with power supply will not cause damage cos it has 15 ohm resistance NOT .15 ohm..it shud be shorted i think

 

[hassam]

question 6 c....see the distance marked 32.4cm is the inter-nodal distance....u halve it to get distance b/w adj node and antinode.....
fig6.1 show antinode-node distance which shud get 16.2 cm by halving suggesting that a.n is .5 cm up from the mout of tube......i hope that clarifies the things