3) A physics student designs a circuit with three lamps, R1 = 50 Ω, R2 = 100 Ω, and R3 = 25 Ω connected in parallel with a 10-volt battery using copper wire. Additionally, an ammeter is placed next to lamp R3 to measure the current flow at a specific point in the circuit.
A) Calculate the current flow measured by the ammeter placed next to lamp R3.
Answers
Answer:
The two crucial characteristics of any galvanometer are its resistance and its current sensitivity. Current sensitivity is the current that gives a full-scale deflection of the galvanometer’s needle — in other words, the maximum current that the instrument can measure. For example, a galvanometer with a current sensitivity of 50 μA has a maximum deflection of its needle when 50 μA flows through it, is at the scale’s halfway point when 25 μA flows through it, and so on.
If such a galvanometer has a 25-Ω resistance, then a voltage of only V = IR = (50 μA)(25 Ω) = 1.25 mV produces a full-scale reading. By connecting resistors to this galvanometer in different ways, you can use it as either a voltmeter or ammeter to measure a broad range of voltages or currents.