How can the resistance of a galvanometer be reduced?

We can protect a galvanometer by using a shunt resistor. The resistance is usually connected in parallel to a galvanometer.

Does galvanometer have fixed resistance?

Galvanometer has small resistance. The construction of the galvanometer is same as that of the ammeter but the only difference between an ammeter and a galvanometer is that the ammeter has additional resistance connected in parallel with the circuit.

How do you increase galvanometer reading?

The deflection of the needle of galvanometer can be increased by:

1. Increasing the number of the turns in the coil.
2. Using a strong magnet.
3. Increasing the speed with which magnet is moved in the coil.

What is the effect of shunt on current sensitivity?

If you want to measure higher current then you can connect a shunt resistor in parallel with the meter and have the two in series with the rest of the circuit. The two together (internal and shunt) will assure that a current smaller than the meter’s limit will flow through it.

What effect will doubling the voltage have on current in a given circuit?

The current is directly proportional to the voltage and inversely proportional to the resistance. Any alteration in the voltage will result in the same alteration of the current. So doubling or tripling the voltage will cause the current to be doubled or tripled.

How can you increase the current sensitivity of a moving coil galvanometer?

So, the correct answer is that the sensitivity of a moving coil galvanometer can be increased by increasing the number of turns of the coil.

How can galvanometer be used to calculate current?

1 Answer

1. Let current I = 1A split as shown in the figure.
2. Current through AB = I1
3. Current through BC = I1 – x.
4. Cureent through AD = I2
5. Current through DC = I2 + x.
6. Current through G = x.
7. ∴ At junction C,
8. I1 – x + I2 + x = I1 + I2 = I = 1 A.

How does galvanometer measure current?

A galvanometer works by deflecting a pointer in response to an electric current flowing through a coil in a constant magnetic field. They were the first instruments used to detect and measure small amounts of current.

Should galvanometer have low or high resistance?

An ideal galvanometer should have zero resistance. In reality, the galvanometer has a very low resistance of 100 ohms. The galvanometer should allow the flow of a small current. The galvanometer deflects when current flows through it.

What will increase the deflection of the galvanometer pointer?

The deflection of the needle of galvanometer can be increased by: Increasing the number of the turns in the coil. Using a strong magnet. Increasing the speed with which magnet is moved in the coil.

What is the effect of shunt resistance on total current of circuit?

The shunt resistance has no effect on the short circuit current while it reduces the open circuit voltage. The series resistance, however, does not change the open circuit voltage but reduces the short circuit current.

How does resistance affect the sensitivity of a galvanometer?

In moving coil galvanometer voltage sensitivity is openly comparative to the number of turns & is inversely proportional to the resistance but on increasing the number of turns length of wire increases which increases the resistance of the wire this shows sensitivity increases on increasing the resistance.

What is the current in moving coil galvanometer?

The current in Moving Coil galvanometer is: I = (C/nBA) × θ The sensitivity of Moving Coil Galvanometer increases by: Increasing the no. of turns and the area of the coil, Decreasing the couple per unit twist of the suspension fiber. Sensitivity increases as the value of n, B, A increases and value of k decreases.

How do you use a galvanometer to measure voltage?

The galvanometer can be used to measure: a) the value of current in the circuit by connecting it in parallel to low resistance. b) the voltage by connecting it in series with high resistance. A galvanometer is converted into an ammeter by connecting it in parallel with a low resistance called shunt resistance.

What is the torsional constant of a galvanometer?

Here k is called the torsional constant of the spring (restoring couple per unit twist). The deflection or twist θ is measured as the value indicated on a scale by a pointer which is connected to the suspension wire. θ= ( nAB / k)I. Therefore θ ∝ I. The quantity nAB / k is a constant for a given galvanometer.