Lab 1 - D’ARSONVAL GALVANOMETER

EXERCISE

Matrix No.  : 192020033

Program     : R2404 Computer Engineering

Date            : 16 September 2021

 INTRODUCTION 

Galvanometer is an instrument for measuring a small electrical current or a function of the current by deflection of a moving coil. The deflection is a mechianial rotation derived from forces resulting from the current.

 RESULTS 

 MULTISIM DIAGRAM 

Diagram for R1 = 510 Ohm

• The diagram above shows the circuit without Rs connected to achieve the value of 30mA. 

1) Rs = 10 Ω

2) Rs = 5 Ω

3) Rs = 2 Ω

Diagram for R1 = 220 Ohm

1) Rs = 10 Ω

2) Rs = 5 Ω

3) Rs = 2 Ω

 CALCULATIONS 

 DISCUSSIONS 

1. Connect the circuit in Figure 1.3 and run the simulation for both load resistance values for 10kΩ and 100kΩ. Observe the measured voltage using voltmeter/DMM and conclude the asnwer with the prove of the diagram. 

 a. Load resistance value = 10k Ω

 b. Load resistance value = 100k Ω

2. Connect the circuit in Figure 1.4 and run the simulation for. The actual voltage across R2 is 7.5 V. Configure the circuit with the voltmeter has an internal resistance of 1 MΩ, 10 MΩ and 100MΩ. Observe the measured voltage using a voltmeter/DMM and conclude the asnwer with the prove of the diagram. 

 a. Internal resistance value = 1 MΩ

 b. Internal resistance value = 10 MΩ

 c. Internal resistance value = 100 MΩ

 CONCLUSIONS 

In this lab we have learned and get to explore some of Multisim instruments in order to design and measure a circuit. More specifically, we learned how to find the internal resistance and the current sensitivity of a galvanometer. The following expression is used to find the value of the internal resistance of the galvanometer (Rg): 

To find the current sensitivity (K), we can use the following formula:

Based on the calculation and measured value in the table, we can observe that as the value of Rs is decrease, the value of R2 is decrease as well.