Some types of fuses used to protect electric meters have resistances of several ohms. Is this objectionable (a) in ammeter circuits and (b) in voltmeter circuits? Why?
Fuses are always connected in series
with the circuit. Therefore, its' resistance should be small compared to the resistance of the circuit.
The circuit of an Ammeter has a much
lower resistance than a Voltmeter. So
the fuse in the Ammeter has a higher
current rating. However, the fuse with the highest current rating has the lowest resistance.
(a) Well, in ammeter circuits, using fuses with resistances of several ohms might be quite objectionable. It's like having a traffic jam on a one-lane road - the flow of current gets restricted, and your ammeter won't be able to accurately measure the current. It's like trying to count peas with chopsticks. Not very efficient, right?
(b) As for voltmeter circuits, having fuses with resistances in the several ohms range isn't that big of a deal. It's like wearing mismatched socks - it might not be perfect, but it won't affect the overall voltage measurement too much. Your voltmeter can still do its job and give you a reasonably accurate reading.
(a) In ammeter circuits, the objectionability of using fuses with resistances of several ohms depends on the specific application and the desired accuracy of the measurements. However, in general, it is usually objectionable to have fuses with significant resistances in ammeter circuits. The reason is that ammeter circuits are typically designed to measure current flowing through a circuit, and the fuse's resistance can introduce errors and affect the accuracy of the current measurement.
When a fuse has a resistance, it creates a voltage drop across it according to Ohm's law (V = I * R). This voltage drop will interfere with the measurement being made by the ammeter, resulting in an incorrect reading. Additionally, the resistance of the fuse could cause a reduction in the amount of current flowing through the circuit, further impacting the accuracy of the measurement.
In summary, using fuses with resistances of several ohms in ammeter circuits can introduce measurement errors and affect the accuracy of current measurements, making it objectionable in most cases.
(b) In voltmeter circuits, the presence of fuses with resistances of several ohms is generally not objectionable. Voltmeters are used to measure voltage across a component or between two points in a circuit. Since voltmeters are typically connected in parallel to the circuit being measured, the resistance of the fuse does not directly affect the voltage measurement.
However, it is important to note that if the resistance of the fuse is significantly high compared to the internal resistance of the voltmeter, it can create a voltage drop that may affect the accuracy of the voltage measurement. Therefore, it is advisable to use fuses with low resistance values in voltmeter circuits to minimize any potential voltage drop and maintain the accuracy of the measurements.
In ammeter circuits, the objectionable resistance of a fuse can have a significant impact. Ammeters are designed to measure the flow of current through a circuit, and they are connected in series with the load. Since ammeters have very low internal resistances, any additional resistance introduced by the fuse can affect the accuracy of the current measurement.
To calculate the effect of the fuse resistance on the ammeter circuit, you can use Ohm's Law. Let's assume the resistance of the fuse is 'R'. When connected in series with the ammeter, the total resistance of the circuit becomes 'R + R_am', where 'R_am' is the internal resistance of the ammeter. The total current passing through the circuit can then be calculated using Ohm's Law as I = V / ( R + R_am ), where 'V' is the voltage across the circuit.
If the resistance of the fuse is significant compared to the internal resistance of the ammeter (R >> R_am), it can lead to a noticeable drop in the measured current and affect the accuracy of the ammeter reading. Therefore, having fuses with resistances of several ohms in ammeter circuits is generally considered objectionable.
On the other hand, in voltmeter circuits, the objectionable resistance of a fuse is not as critical. Voltmeters are designed to measure the voltage across a circuit, and they are connected in parallel to the load. Since voltmeters have very high internal resistances, the additional resistance introduced by the fuse has a negligible effect on the overall circuit.
In summary, the objectionable resistance of a fuse is more problematic in ammeter circuits due to the potential impact on current measurement accuracy. In voltmeter circuits, the fuse resistance is generally not a significant concern.