Q & A: Short Circuit

Q:
What happens to an electrical circuit when it "shorts"?
- T.J. (age 15)
Douglass High School, Atlanta, GA, Fulton
A:
That's a good question! If something is considered a short circuit, or "short", it means that there is no resistance along the line. In order to short something, let's say a resistor, all you have to do is to connect a wire from where the resistor starts to where it ends. Now all of the current will flow through the wire instead of the resistor. This will change the current and voltage in the rest of the circuit, which can be very bad if the short was accidental. Usually, when people say a circuit has "shorted", they just mean that some part(s) of the circuit was accidentally shorted, which caused the other parts of the circuit not to work properly.

I hope this helps!
~Ann

(published on 10/22/2007)

Follow-Up #1: Flying parrot in a cage

Q:
a wire cage with a parrot sitting in it is suspended from a spring balance.the parrot starts flying.what will be the reading of the spring balance?
- jinia (age 17)
kolkata,west bengal,india
A:
Hello Jinia,

That is an interesting question.
It really depends on whether the downwards current of air, which is being pushed downwards by the flapping of the parrot's wings, exerts a downward force on the bottom of the cage.

For example, if the bottom of the cage is made up of a wire mesh, the downwards current of air would almost go right through it so the spring balance would no longer measure much of its weight.
However, if the bottom of the cage is able to capture the downwards current of air (such as a thin piece of wood would),  the downwards current of air will exert a downward force on the cage, and thus the spring balance will still pick up most of the parrot's weight.

I would also like to add that if the parrot was in an enclosed cage (like a sealed box). The time-averaged weight of the box (as measured by the spring balance) would still be the same whether the parrot was flying or not.

Maurice

(published on 03/17/2012)