Subject > Physics > Physics IV > Thermal-Chemical Effects of Currents
Thermal-Chemical Effects of Currents
Numerical 10
10. A sensitive microphone cannot withstand currents greater than 0.05A. When connected across a thermocouple of emf 8.5 mV, the current in a very low resistance ammeter placed in series in the circuit reads 34 mA. Calculate the resistance of the microphone.
Suggested solution:
If R is the resistance of the microphone and r is the resistance of the ammeter, then
