The filament battery of the electronic lamp has an EMF of 6.0 V; for the lamp to glow, a voltage of 4 V

| February 5, 2021 | education

The filament battery of the electronic lamp has an EMF of 6.0 V; for the lamp to glow, a voltage of 4 V is required at a current of 80 Amps. internal resistance of the battery 0.2m. what should be the resistance of the resistor, which must be connected in series with the lamp filament in order to avoid overheating?

The total voltage drop in the circuit must be equal to the EMF. Since the voltage drop in the lamp is 4 V, the total voltage drop in the rest of the circuit is:

Uо = 6 – 4 = 2 V.

According to Ohm’s law, the total resistance Rо of the rest of the circuit is equal to the voltage Uо = 2 V divided by the current I = 80 mA = 0.08 A:

Rо = Uо / I = 2 / 0.08 = 25 Ohm.

Subtracting the internal resistance of the battery Rb = 0.2 Ohm from the total resistance Rо, we obtain the resistance R of the additional resistor

R = Ro – Rb = 25 – 0.2 = 24.8 Ohm.



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