Short circuit current?

Question

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What's the purpose of the R load in the second circuit diagram? What happens after it is connected?

Answer 1

R load represents the 10k ohm resistance of whatever electrical device that is connected across R2. In this particular case nothing will happen when R load is connected because the amp meter has R load and R2 both shorted. The amp meter should be reading 1.5 miliamps.

If the amp meter is removed and R load is connected across R2 then 5 volts will be present across R load and it will draw 0.5 miliamps of current.

Answer 2

I would guess that whoever drew the circuit mistakenly put an ammeter in it instead of a voltmeter ...

and the purpose of the excercise is, perhaps, to show the limitations of a simple resistive voltage divider.

Answer 3

If that "R Load" means 'reactive load`, it will contribute

to the short circuit current.

Answer 4

I don't know what the other answer is about, ignore it.

Purpose? You'd have to ask whoever wrote the problem what the purpose is. To test the student's understanding is my guess.

Initially you have a voltage divider of 1/2, so the voltage out is 7.5 volts.

adding the other 10k, you get an equivalent of 5k, so the voltage divider is 5/15 or 1/3, so the voltage out is 5 volts. BUT the ammeter shorts out the Vout, so if that is really an ammeter, the voltage out is zero or close to zero.

And the ammeter would read 15V/10k or 1.5 mA.

.

Answer 5

The Battery Eliminator Circuit, or BEC, is one of the tools at our disposal to reduce weight in our electric models. A typical four-cell 600mAh nickel cadmium (NiCd) battery supplied with most radio systems weighs about 3.3 oz (94 g), a significant fraction of the weight of a typical beginner's electric model (such as a Great Planes ElectriCub or Spectra). Lighter batteries are available, but with the trend towards even smaller and lighter models, even a 1.5 to 2 oz (43 to 57 g) battery is too much to carry. The model will still fly, but it's flight characteristics will be compromised.

The BEC lets us eliminate the receiver battery, using the motor battery to provide power to the radio system instead. This has some ramifications as to where and how we can use a BEC, and of course, it also means we can't use BEC in a glow powered model, or a pure sailplane.  

Answer 6

The first diagram is a simple voltage divider giving a voltage of 7.5 volts

The current in the circuit is 15/20000 = 0.75mA

When the load resistor is connected the circuit changes. The parallel section gives a a total resistance of 5K so the circuit now gives a Vout of 5 volts and the total current goes up to 1mA.

The ammeter looks as if it is drawn in the wrong place and could have 2 possible positions

a. In series with R1 measuring the total current or

b. In series with the load measuring the load current 5/10000 = 0.5mA

If the ammeter is in the correct position then as previous answer it actually shorts out R2 and the load thus circuit current goes up to 15/10000 = 1.5mA

So it is possible that the question is in 3 parts

1.  What is the circuit current with R1 and R2 connected ? V out = 7.5 Volts and circuit current = 0.75mA

2.  What is the effect of connecting the load?  The circuit current increases to 1 mA the output voltage drops to 5V and the load current is 0.5mA

3.  What is the effect of connecting the ammeter The circuit current increases to 1.5mA  the output Voltage drops to zero and the load current drops to zero