K.C.S.E Physics Q & A - MODEL 1996PP2QN02

K.C.S.E Physics Q & A - MODEL 1996PP2QN02

(a) Given a bar magnet, an iron bar and a string
(i) Describe a simple experiment to distinguish between the magnet and the iron bar 
(ii) State with reasons the observation that would be made in the experiment 
(b) In an experiment to magnetize two substances P and Q using electric current, two curves ( graphs) were obtained as shown in figure 

Using the information in Fig 1 explain the difference between the substances P and Q with references to the domain theory 

answers

(a) (i) Each bar is suspended at a time using the string;
 The suspended bar is allowed to rest;
 Its orientation is observed and recorded;
This is repeated several times for confirmation
 (ii) The bar magnet settles in the N – S specific direction, due to its
Interaction (l) with magnetic field of the earth (l)
The iron bar settles in any direction; (l) because it does not have a magnetic field to the interact with that of the earth; (l)
(b) P and Q are magnetized to the same level, by applying two different (l) current lp and lq such that lq > lp (l)
Thus Q requires greater magnetizing power, (l) since its domains are more difficult to align; (l) P is easier to magnetize, since its (l) domain are more easily aligned: