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Ask the Bridge
I
recently read a story in the Boston Globe estimating that in the United
States there are 220,000 children as young as six years old who are latchkey
kids. What might be the long-term effects of this on children? Will they
grow up to be independent adults or perhaps be more needy in their relationships
in adulthood?
"The research we have can't tell us definitively what these children will be like as adults," says Deborah Belle, a CAS associate professor of psychology, "although your speculations are quite reasonable. Research does show that young children who spend considerable time without adult supervision are often lonely, bored, and afraid, and their schoolwork can suffer. Older children can experience problems with unsupervised time, too, doing poorly in school and getting involved in risky activities. Some children of all ages are able to rise to the occasion and become particularly responsible and independent. Since parents in this country work longer hours than those in any of the other industrialized nations and our government does less to support families through subsidized after-school programs, parental leaves, or income support to parents, we are actually conducting a vast, unmonitored experiment with the welfare of many of the nation's children."
Why are there so many kinds of batteries out there? What's the difference between AAA, AA, C, D size batteries, and why can't there be a one-size-fits-all battery?
"When a battery is connected to a radio, CD player, or cell phone,
it provides two things," says Mark Horenstein, an ENG professor of
electrical engineering. "The first is voltage, which is analogous
to the pressure behind a kitchen water faucet. The second is current,
or flow rate of electricity, which is similar to the actual amount of
water that comes out of the faucet when it is turned on.
"The voltage of a battery is determined by the chemicals that are
contained inside it, whereas the current capability of the battery is
determined by its volume. For a given required voltage, devices that need
only small amounts of current can run from batteries of smaller volume,
such as AAA or AA sizes. In contrast, devices that require larger amounts
of current must run on batteries of larger volume, such as C or D sizes.
If an appliance is run from a battery that is too small to provide the
needed current, the voltage of the battery will be reduced below an acceptable
level. Incidentally, AAA through D size batteries produce a voltage of
about 1.5 volts. A rectangular 9-volt battery actually has six small 1.5-volt
batteries inside it, all connected in series to produce a total voltage
of 9 volts."
"Ask the Bridge" welcomes readers' questions. E-mail bridge@bu.edu or write to "Ask the Bridge," 10 Lenox Street, Brookline, MA 02446.
4
October 2002
Boston University
Office of University Relations