Electric circuits: l’experiment , Summaries of Physics

Download Electric circuits: l’experiment and more Summaries Physics in PDF only on Docsity!

lOMoARcPSD|

K. A. Charles,

Electric circuits: l’experiment

Experiment # 2 – DC Meters

= = 4.651 V

R + R + R R / R

= = 4.644 V

R R S

DMM 19.645 19.845 (ideal) 1. 50 mA ammeter 18.900 19.626 3. Calculations (Theoretical): DMM: I^ =

V S

R

100.789 =^ 0.019845^ A^ =^ 19.845 mA

50 mA ammeter: I^

VS

m (^) ( R + R am )

= 0.019626 A = 19.626 mA

Table 3.5: Circuit Element Measured Voltage (V) Theoretical Voltage (V) % Error DMM 4.000 4.651 (ideal) 13. DC voltmeter 3.970 4.644 14. Calculations (Theoretical): DMM: V^ =^

R 2

V

1 +^2

DC voltmeter : V^ =^

R 2

V

1 2 1 2 vm

S

Conclusion: In the lab we were able to measure and clearly see the difference in accuracy between the DMM and the DC voltmeter and ammeter. In each case, the DMM was always more accurate, and it can be concluded that the relative resistance value of the DMM ammeter is lower than the 50 mA ammeter. We can make this conclusion because when looking at the equation for current, the resistance of the ammeter was added to the 100 Ω resistor, so the smaller the resistance of the ammeter, the more accurate the answer. It can also be noted that the voltmeters appear to have a very large resistance, as measured in the DC voltmeter with a resistance of 50334 Ω , because voltmeters are connected in parallel, so the larger the resistance is, the more accurate the answer. When measuring the current the percent errors came out to be 1.008 % and 3.699 % which were accurate, however when measuring the voltage, the percent errors came out to be 13.997% and 14.513 %. The larger percent errors were most likely caused by a bad connection in the circuit, since many more wires were needed for the parallel circuit, some might have not been connected as well. Another reason we might have had more error for the voltage than for the current may be due to the resistors heating up from the higher voltage of 20V used for measuring voltage compared to the 2V used for measuring current.