J2 H2 Physics 2008 prelim questions from top junior colleges(JCs). Topic is Alternating current.

1. 1. C
2. A
3. C
4. D
5. C
6. A
7. A
8. D
9. B
10. B
11.
(a)(i)
Alternating voltage can be stepped up or down with little power loss whereas direct voltage cannot be stepped up or down easily.
(ii) Step-up transformer with turn ratio 2.
(iii) Assuming no power losses in the transformer,
120Ip = 1000
Ip = 8.33 A r.m.s.
(b)(i)
Cheaper to install and maintain.
(ii) Can be blown against buildings in windy conditions.