Two 1.50-V batteries—with their positive terminals in the same direction—are inserted in series into the barrel of a flashlight. One battery has an internal resistance of 0.320 Ω, the other an internal resistance of 0.140 Ω. When the switch is closed, a current of 600 mA occurs in the lamp. (a) What is the bulb's resistance?

Respuesta :

Answer:

[tex]R=4.54\ \Omega[/tex]

Explanation:

It is given that,

Voltage of the battery, V = 1.5 V

Internal resistance of battery 1, [tex]r_1=0.32\ \Omega[/tex]

Internal resistance of battery 2, [tex]r_2=0.14\ \Omega[/tex]              

Current flowing in the lamp, [tex]I=600\ mA=600\times 10^{-3}\ A=0.6\ A[/tex]

Total internal resistance of tow batteries,

[tex]r=r_1+r_2[/tex]          

[tex]r=0.32+0.14[/tex]

[tex]r=0.46\ \Omega[/tex]

Let R is the resistance of the bulb. Let V is the total emf of the circuit. It is given by :

[tex]V=I(R+r)[/tex]

[tex]R=\dfrac{V}{I}-r[/tex]

[tex]R=\dfrac{2\times 1.5}{0.6}-0.46[/tex]

[tex]R=4.54\ \Omega[/tex]

So, the resistance of the bulb is 4.54 ohms. Hence, this is the required solution.