230. The scientist who first sent electromagnetic waves to distant places was
   (a) James Clerk Maxwell
   (b) Heinrich Hertz
   (c) Thomas Alva Edison
   (d) Baird
Ans: (c)
231. Like magnetic poles
   (a) attract each other
   (b) repel each other
   (c) neither attract nor repel
   (d) attract or repel depending upon the conditions
Ans: (b)
232. The strength of an electromagnet can be increased by
   (a) increasing the length of the coiled wire
   (b) increasing current supply
   (c) increasing the size of the iron core
   (d) All the above
Ans: (d)
233. Among the following the most suitable material for the core of an electro-
   magnet is
   (a) steel
   (b) wood
   (c) soft iron
   (d) copper
Ans: (c)
234. If a bar magnet is broken into two pieces
   (a) both pieces will lose their magnetism
   (b) one piece will have North Pole on both ends and the other South Pole on
       its both ends
   (c) each will remain a magnet with North Pole at one end and South Pole at
       the other
   (d) the longer piece will behave as a bar magnet while the smaller will have
       no magnetism at all