In AC bridge galvanometer is not used because the rotating torque is dependent on the average current that is passing through the coils of a galvanometer.Therefore, the galvanometer is not used in the AC bridge.
Does galvanometer work in AC?
Basically, no. A galvanometer is a moving coil instrument, where the magnetic force applied by the current is opposed by a (hair) spring, so that the deflection is proportional to the current. An AC current would make the force oscilate, but the inertia of the moving element would probably make this invisible.
Why galvanometer does not show any deflection?
When the magnet is held stationary, the galvanometer shows no deflection.This indicates that when there is a relative motion between the coil and the magnet a current is induced in the coil. This current gets detected with the help of a galvanometer.
What can we use in place of galvanometer in bridges?
Answer: A galvanometer can be turned into an ammeter by parallely connecting a resistance in the electric circuit.
Why We Use Headphone in Anderson Bridge?
It enables us to measure the inductance of a coil using capacitor and resistors and does not require repeated balancing of the bridge. The connections are shown in Fig: 1. The bridge is balanced by a steady current by replacing the headphone H by moving coil galvanometer and A.C source by a battery.
Why is galvanometer used?
galvanometer, instrument for measuring a small electrical current or a function of the current by deflection of a moving coil. The deflection is a mechanical rotation derived from forces resulting from the current.
Does galvanometer have positive and negative terminals?
Galvanometer has positive and negative terminals.The resistance of the coil of the galvanometer is called the resistance of the galvanometer.
Why AC current is used in Wheatstone bridge?
Key Differences Between AC and DC Bridge
The bridge which is used for measuring the unknown impedance of the circuit is known as the Wheatstone bridge.The AC bridge uses the AC supply. The DC bridge uses the DC supply for measuring the resistance. In AC bridge the current is detected by using the AC detector.
Why does a DC ammeter Cannot read AC?
DC ammeters can measure constant current i.e. direct current. Hence, alternating current cannot be measured by DC ammeter because the average value of current for the complete cycle is zero.
When an alternating current is passed through a moving coil galvanometer it shows no deflection Why?
When an a.c. passes through the galvanometer, it shows no deflection , why ? A moving coil galvanometer measures average value of current, which is zero for a.c. over a cycle. So, galvanometer shows no deflection.
Can we use ammeter instead of galvanometer?
Solution: Yes, we can use a galvanometer as an ammeter in the circuit. We can convert it into an ammeter. For this conversion, a low resistance known as shunt resistance has to be connected in parallel to the galvanometer.
What happens if the galvanometer and cell are interchanged?
If the galvanometer and the cell are interchanged then the balance point remains unchanged. Hence, the galvanometer will not show any current and there will be null deflection.
What is the role of galvanometer in Metre bridge experiment?
If we are doing the meter bridge experiment in the lab, by adjusting the value of resistance box the galvanometer will show the null deflection. Then we will find the value of L1 and L2. After substituting these values in the equation we will find the unknown resistance.
What is the significance of capacitor in Maxwell Bridge?
What is the significance of capacitors in a Maxwell bridge? Explanation: In a Maxwell inductance capacitance bridge, the capacitors are cheaper when compared to a stable and accurate standard value of inductors.
What is the disadvantage of Maxwell Bridge?
The disadvantages of a Maxwell Bridge are: The variable standard capacitor is very expensive. The bridge is limited to measurement of low quality coils (1 < Q < 10) and it is also unsuitable for low value of Q (i.e. Q < 1) from this we conclude that a Maxwell bridge is used suitable only for medium Q coils.
What is the use of Kelvin Double Bridge?
A Kelvin bridge, also called a Kelvin double bridge and in some countries a Thomson bridge, is a measuring instrument used to measure unknown electrical resistors below 1 ohm. It is specifically designed to measure resistors that are constructed as four terminal resistors.
Why galvanometer is not used to measure current?
The galvanometer is a very sensitive device. Hence, it may get damaged when a strong current is passed through the galvanometer.The galvanometer resistance is larger than the ammeter, if it is connected in series it will reduce the current flow through the circuit.
Why galvanometer is used instead of voltmeter?
As a Measuring Device
A galvanometer can be calibrated to measure current as well as voltage. A voltmeter only ever measures voltage.
Is galvanometer better than ammeter?
The accuracy of the galvanometer is less as compared to the ammeter. The galvanometer is only used for measuring the direct current, whereas the ammeter is used for measuring the both the direct and alternating current. The sensitivity of the galvanometer is more as compared to the ammeter.
Why galvanometer does not have positive and negative terminal?
The galvanometer do not have any positive and negative terminals, the pointer can point in any direction with zero as the reference point at the centre. It shows currents (both ac and dc) which has a desired direction of flow of electrons.. So Galvanometer does not have any electrolytic terminals
Why is galvanometer a moving coil?
Torque acts on a current-carrying coil suspended in the uniform magnetic field. Due to this, the coil rotates. Hence, the deflection in the coil of a moving coil galvanometer is directly proportional to the current flowing in the coil.
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