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kira506
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I'm talking about the primitive rheostat with coils and a slide and such , why when we inc. The resistance of rheostat does Vext inc and Vint dec. ?
Of course it's different! I = V/R always and it's that total series resistance that counts.("Unless the current is different
sophiecentaur said:This is a bit like trying 'grasp' how the supermarket bill works. It's down to the sums and the very basics of electricity more than anything. You will be able to feel that you have a grasp when you follow the sums through.
Have you drawn the circuit?
Mark the rheostat as R1 and the Load as R2. If Vin is the supply voltage then
The total current I through the two resistors will be Vin/ (R1+R2)
This current is, of course, dependent upon the two resistor values.
You say:
Of course it's different! I = V/R always and it's that total series resistance that counts.
Clearly, I will get greater as R1 goes down (i.e. as the total resistance decreases).
So the current through the load will increase (Same current round the whole loop)
That means that the volts across the load Vout = IR2, will increase because I has increased.
Naturally, if the volts across the load have increased, the volts across the rheostat will have decreased because there is the same total supply voltage across the two resistors and it's the sum of the two volts.
The smaller resistor gets the smaller share of the total voltage.
A rheostat is an electrical component that is used to vary the resistance in a circuit. It typically consists of a coil of wire wrapped around a cylinder with a movable contact arm that can slide along the coil to change the amount of resistance in the circuit.
A rheostat affects current by changing the resistance in the circuit. As the resistance increases, the current flowing through the circuit decreases. This is because Ohm's law states that current is inversely proportional to resistance.
The relationship between rheostat resistance and current is inverse, meaning that as the resistance increases, the current decreases. This can be described by Ohm's law, which states that current (I) is equal to voltage (V) divided by resistance (R), or I = V/R.
When a rheostat is added to a circuit, the voltage remains constant. However, the voltage drop across the rheostat will change depending on the resistance set by the rheostat. The total voltage in the circuit will still be equal to the sum of the voltage drops across each component in the circuit.
A rheostat can be used to control the brightness of a light bulb by changing the amount of current flowing through the circuit. As the resistance is increased, the current decreases, resulting in a dimmer light. Similarly, decreasing the resistance will increase the current and make the light bulb brighter.