Voltage and potential difference are the same thing. Nobody out of school uses the latter term. Voltage is the potential in an electrical circuit to cause the flow of current (ie, electrons). wikipedia: Voltage is commonly used as a short name for electrical potential difference.
Population of Jamaica 2014. As of 1 January 2015, the population of Jamaica was estimated to be 2 767 704 people. This is an increase of 0.73 % (20 112 people) compared to population of 2 747 592 the year before. In 2014 the natural increase was positive, as the number of births exceeded the number of deaths by 34 785. Due to external migration, the population declined by 14 672. The sex ratio of the total population was 0.969 (969 males per 1 000 females) which is lower than global sex ratio.
By 1700 Jamaica was awash with sugar plantations and Jamaica's population was comprised of 7,000 English to 40,000 slaves. The sugar industry grew quickly in Jamaica -- in 1672 there were 70 plantations producing 772 tonnes of sugar per annum -- growing in the 1770s to over 680 plantations. By 1800, it was 21,000 English to 300,000 slaves, which increased to some 500,000 slaves by the 18th century.