working on simple series ckt with child and am a little stumed -
thanks in advance

Voltage source - 3- 1.5V batteries 2A
2 loads - 1- is light bulb 1- is small motor - do not know ratings (sorry)

when in parallel both work fine
when in series - regardless of order - light will not light - motor spins fine.

 

Can you sketch, scan, and post your circuit here?

hgmjr

 

here it is.

 

I suspect that if you hold the motor shaft in the series circuit the light will light.

The parallel circuit allows the optimum voltage and current (power) to be delivered to the load. Another way to state this is that the power (voltage time current) is most efficiently delivered to the load. That is because the output resistance associated with each of the battery individually is combined in parallel in the parallel circuit but this same resistance is in series in the series circuit.

With the series circuit. the power needed by the motor and light is split up. The power needed to power the motor is less than the power needed to light the light. Thus the motor spins bu tthe light does not light.


hgmjr

 

In the series connection where the light does not come on, try restraining the motor spindle with your fingers - carefully, don't let a little child do this in case he hurts himself. What happens???

OOps, beaten to it!

Edit: The motor should draw more current if it is required to deliver more torque (turning effort). When it runs with no load, it only requires as much current as is needed to supply its internal losses.

 

thanks - all