So the brightness factor equals 2.512 raised to the power of the magnitude difference. In the case of Venus and Jupiter, their 2.2 magnitude difference works out to a light ratio difference of 7.59. Thus, Venus will appear nearly eight times brighter than Jupiter. Check it out for yourself.
Contrary to popular belief, conjunctions between Venus and Jupiter are not rare events; in fact they occur on average about every 13 months. Interestingly, the sidereal revolution periods (that is, the time it takes them to make one full orbit relative to the stars) of Venus, Earth and Jupiter are, respectively, 224.7008, 365.2564, and 4332.5894 days.
So 39 such periods of Venus are virtually equal to 24 orbital periods of the Earth and 2 periods of Jupiter. For this reason, circumstances involving specific conjunctions between Venus and Jupiter repeat under almost identical conditions after a time span of just over 24 years.
On March 5, 1988, Venus and Jupiter were in conjunction, with Venus passing 2.2 degrees north of Jupiter. A little more than 24 years later brings us to this week. On March 13, 2012, Venus will pass 3 degrees north of Jupiter.