Page 262 - Practical English Usage 3ed - Michael Swan, Oxford

c economic and economical
Economic refers to the science of economics, or to the economy of a country. economic theory economic problems
Economical means 'not wasting money'.
all economical little car an economical housekeeper
d electric and electrical
Electric is used with the names of particular machines that work by electricity. an electric motor electric blankets
Note also: an electric shock; an electric atmosphere (full of excitement). Electrical is used before more general words.
electrical appliances electrical equipment electrical component electrical engineering
e historic and historical
Historic is used especially for historically important places, remains, customs etc, and for moments which 'make history'.
We spent ollr holiday visiting historic houses and castles in France.
Ollr two countries are about to make a historic agreement.
Historical means 'connected with the study of history' or 'really existing in history'.
historical research a historical novel
historical documents Was King Arthur a historical figure?
f magic and magical
Magic is the more common word, and is used in a number of fixed expressions.
a magic wand (= a magician's stick)
the magic word a magic carpet
Magical is sometimes used instead of magic, especially in metaphorical senses like 'mysterious', 'wonderful' or 'exciting'.
It was a magical experience.
9 politic and political
Politic is a rather unusual word for 'wise', 'prudent'.
I don't think it would be politic to ask for a loan just now.
Political means 'connected with politics'. political history a political career
4 adverbs
Note that whether the adjective ends in -ic or -ical. the adverb ends in -icaUy (pronounced /Ikli/). The one common exception is publicly (NOT prtblietJlly).
5 nouns ending in -ics
Many nouns ending in -ics are singular (e.g. physics, athletics). Some can be
either singular or plural (e.g. mathematics, politics). For details, see 524.3.
-ic and -ical 254
page 230