1995 past paper

[S.McGrath]

paper 1
Q25-28
paper 2
i cant get Q6d) (ii), Q8b)(ii) & c, Q9b) and the whole of Q10

[ANDYQ]

q5a please paper 2

[Admin]

I left the paper in school so I do not know what the questions are, can you both please give me more info and I'll give you some pointers.

[Connor Einstein]

Andy, in question 5a you can split it up so that you get a parallel circuit with two resistors at the top one in the middle then two again then all you do is :
1/Rt= 1/20+1/20+1/10
1/Rt= 1/5
Rt=5

[Connor Einstein]

steve Q6d) X= transistor and Y= relay so when the door is closed the opamp gives a reading of 0v and does not do anything. however when the door opens the vout becomes 5v and is more than the 0.7v required to turn x on and so the relay pulls in the switch because it is an electro magnet and this gives the alarm the voltage it needs to sound as the 12v supply is now connected.

[Connor Einstein]

i think question 8ii is E=QV then Ek= your answer to the previous answer + your E=QV answer but not really sure

[Connor Einstein]

im stuck on the rest as well although in q10ai is it not just a simple circuit with a PN block diagram down the bottom, bi I thoought was 0.5 volts then for ii) decreases then do two equations one from the start of the graph then another from the end to prove that R goes down

Hope this is of help

[S.McGrath]

cheers connor