One day Canelina found a little battery of 12V inside a garage door remote control.
She was very excited as now had the same voltage as the powerful battery of a car.
She thought she could power everything that operates with 12V. Her laptop, motors, fans, portable TV etc.
To her amazement she found it did not work.
Disappointed she bought with her friend the patient tortoise a voltmeter to check what happens.
Every time they connected almost anything, the terminals of her battery were reduced to very few if any volts at the speed of light.
Crying they went to the two wise seagulls on the beach who were standing carelessly on their favorite rock inside the sea.
They said it is the law of concervation of energy.
The voltage therefore drops inside the little battery.
The the world external to the battery it appears as if there is a resistor in series inside.
Every time we try to draw current there is voltage drop according to Ohm's law.
And what about the car battery?
It still has and internal resistance but it is much much smaller. So there is much less voltage drop when something is carefully and with all precautions connected to it and it works.
Microphones have usually and output impedance of 200 ohms.
Canelina jumped up with joy.
And they all started dancing on the beach while singing under the rays of sun that do not leave any shadow to truth.
Reference:
Electronics - Neil Storey
No comments:
Post a Comment