A battery, an ammeter and a variable resistor connected in series.A voltmeter is connected across fixed resisitor.The value of variable resistor is reduced.What would happen to ammeter and voltmeter reading?
If the value of the variable resistor is reduced, there are two impacts on the ammeter and voltmeter readings:
1. Ammeter Reading:
When the value of the variable resistor is reduced, it will decrease the total resistance in the circuit. According to Ohm's Law (V = IR), where V is the voltage, I is the current, and R is the resistance, if the resistance decreases, the current will increase (assuming the voltage remains constant). Therefore, the ammeter reading will increase.
2. Voltmeter Reading:
The voltmeter is connected across the fixed resistor, which means it is measuring the voltage drop across the fixed resistor only. As the value of the variable resistor is reduced, the total resistance in the circuit decreases. This leads to a decrease in the overall voltage drop across the entire circuit, including the fixed resistor. Consequently, the voltmeter reading will decrease because it measures the voltage drop across the fixed resistor.
In summary, when the value of the variable resistor is reduced, the ammeter reading will increase, while the voltmeter reading will decrease.
When the value of the variable resistor is reduced in a circuit consisting of a battery, an ammeter, a variable resistor, and a fixed resistor in series, the following will happen to the ammeter and voltmeter readings:
1. Ammeter Reading: The ammeter measures the current flowing through the circuit. As the value of the variable resistor is reduced, the total resistance in the circuit decreases. According to Ohm's Law (V = I*R), as the resistance decreases, keeping the voltage (V) (from the battery) constant, the current (I) will increase. Therefore, the ammeter reading will increase because the current flowing through the circuit has increased.
2. Voltmeter Reading: The voltmeter measures the voltage across a component in the circuit. In this case, it is connected across the fixed resistor. As the value of the variable resistor is reduced, the total resistance of the circuit decreases. According to Ohm's Law, if the current (I) in the circuit has increased (as explained in point 1), and the resistance of the fixed resistor remains the same, the voltage (V) across the fixed resistor will also increase. Consequently, the voltmeter reading will increase because the voltage across the fixed resistor has increased.
In summary, as the value of the variable resistor is reduced, the ammeter reading will increase as the current flowing through the circuit increases, and the voltmeter reading will increase as the voltage across the fixed resistor increases.
the voltmeter has very high resistance, so it is effectively not part of the circuit. It draws almost no current.
The ammeter has very low resistance, so it is effectively invisible as a load.
as the resistor goes up, the current goes down. I = E/R
The voltage across the resistor stays constant, however, so since the voltmeter measures that voltage, its reading also does not change.