Learn the Resistance of Galvanometer by Half Deflection Method with this Free PDF Download
Resistance of Galvanometer by Half Deflection Method: A PDF Guide
If you are interested in learning how to determine the resistance of a galvanometer by half deflection method and its figure of merit, then you might want to download a PDF guide on this topic. A galvanometer is a device that is used to detect very low current in a circuit. Its working is based on the principle that a coil placed in a uniform magnetic field experiences a torque when an electric current is set up in it. The deflection of the coil is determined by a pointer attached to it, moving on the scale.
resistance of galvanometer by half deflection method pdf download
The resistance of the galvanometer can be found by using a simple circuit that consists of a battery, a high resistance box, a low resistance box, two one-way keys, and a voltmeter. The circuit diagram is shown below:
The procedure for finding the resistance of the galvanometer by half deflection method is as follows:
Connect the circuit as shown in the figure. Make sure that all the plugs in the resistance boxes are tight.
Eliminate the high resistance from the high resistance box and insert plug key K1 only. Adjust the value of R to make the deflection maximum both in number and within the scale. Note the deflection θ.
Now insert the key K2 without changing the value of R. Adjust the value of S such that the value of the deflection reduces to half of θ, i.e. θ/2. Note down the value of resistance S.
Repeat steps 2 and 3 three times and obtain different values of R for different values of S.
Find the value of the E.M.F of one of the cells with the help of a voltmeter.
The resistance of the given galvanometer as found by half deflection method is given by G= (RS)/ (R-S) where R is the resistance connected in series with the galvanometer and S is the shunt resistance . By knowing the values of R and S, you can calculate G using this formula.
The figure of merit (k) of the galvanometer is defined as the current required for deflecting the pointer by one division. That is k = I/θ where I is the current and θ is the deflection. For determining the figure of merit of the galvanometer, you need to open the key K2 in the circuit arrangement. Using E = I (R + G) where E is the emf of battery and G is the galvanometer resistance, you can calculate k using this formula.
Some advantages of using the half deflection method to determine the resistance of a galvanometer are:
It is a simple and easy method that does not require any complex calculations or instruments.
It is a reliable method that gives accurate results as the deflection is measured at two points on the same scale.
It is a convenient method that can be performed with any galvanometer and any battery of suitable voltage.
Some precautions that should be taken while performing the half deflection method are:
All the plugs in the resistance boxes should be tight.
The e.m.f of the cell or battery should be constant.
High resistance from the high resistance box should be introduced in the circuit otherwise excessive current will flow through the ammeter and it can be damaged.
If you want to download a PDF guide on resistance of galvanometer by half deflection method, you can click on the link below. This PDF guide will provide you with more details, diagrams, examples, and exercises on this topic. You can also print it out and use it as a reference or a study material.
Download PDF Guide on Resistance of Galvanometer by Half Deflection Method
In conclusion, resistance of galvanometer by half deflection method is a useful technique to measure the resistance of a galvanometer and its figure of merit. It is based on the principle that the current through a galvanometer is inversely proportional to its deflection. By using a simple circuit with a battery, a high resistance box, a low resistance box, two one-way keys, and a voltmeter, you can find the resistance of the galvanometer by making its deflection half. You can also find the figure of merit of the galvanometer by using the formula k = I/θ where I is the current and θ is the deflection. This method has some advantages such as simplicity, reliability, and convenience. However, you should also take some precautions such as ensuring tight plugs, constant e.m.f, and high resistance in the circuit. If you want to learn more about this method, you can download a PDF guide on this topic from the link given in this article.
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