Help with 3 questions (Physics paper 1)

[Ritter]

Hey I'd like someone to explain to me 3 questions in physics o.l (Code: 0625) paper 1 from the old exams (before 2000s)
Whether I don't understand the question or the mark scheme is wrong (some old mark schemes contain mistakes)

Anyway here is the first

Is the circuit of the electric bell still in the syllabus
If yes, could you please explain it for me
if no, then ignore it

second:

Mark Scheme says : A
I answered B


third:

Mark Scheme : A
i understand it , but i don't understand why choice C is wrong


Thanks in advance

 

[Ibosk8mafia]

Ok here we go *clears throat*
Question 1: Yes it is included and A is the right choice because in an electric bell a circuit breaker has to be present . The gong is not struck only once *duhh*. Anyways so when the switch is pressed the electromagent is magnetised and it attracts the iron bar so it hits the gong when the iron is attracted it breaks the contact and circuit is not complete now so the electromagnet demagnetises and this process repeats as long as the switch is closed.

Question 2: COM shifts towards added weight to balance so the answer is A because not one person is on the top floor. Now you may say that more people are on the bottom than on the top in B , but do you have any proof that the person on top is not heavier than the combined total of the people in the bottom layer. NO . Never make assumptions and expand your library of knowledge. Be logical and always link your knowledge.

Question 3: A is the right answer and C is wrong because if an iron bar is placed in ac solenoid then it will possess alternating magnetism.

 

[Ritter]

Ok here we go *clears throat*
Question 1: Yes it is included and A is the right choice because in an electric bell a circuit breaker has to be present . The gong is not struck only once *duhh*. Anyways so when the switch is pressed the electromagent is magnetised and it attracts the iron bar so it hits the gong when the iron is attracted it breaks the contact and circuit is not complete now so the electromagnet demagnetises and this process repeats as long as the switch is closed.

Question 2: COM shifts towards added weight to balance so the answer is A because not one person is on the top floor. Now you may say that more people are on the bottom than on the top in B , but do you have any proof that the person on top is not heavier than the combined total of the people in the bottom layer. NO . Never make assumptions and expand your library of knowledge. Be logical and always link your knowledge.

Question 3: A is the right answer and C is wrong because if an iron bar is placed in ac solenoid then it will possess alternating magnetism.

Thanks a lot for your help