In the figure what value must R have if the current in the c

In the figure what value must R have if the current in the circuit is to be t .4 mA? Take epsilon_1 = 1.6 V, epsilon_2 - 3.0 V, and r_1 = r_2 = 2.9 ohm. (b) What Is the rate at which thermal energy appears m R? Click If you would like to Show Work for this question:

Solution

E1=1.6V

E2=3V

Current i = 1.4 mA = 1.4 x10 ^-3 A

Internal resistances r1 =r2 = 2.9 ohm

Apply Kirchoff\'s second law to the loop you get,

E2-E1= i(r1+r2+R)

3-1.6 = (1.4 x10 ^-3) (2.9+2.9+R)

1.4 = (1.4 x10 ^-3) (2.9+2.9+R)

   1 = 10 ^-3 (2.9+2.9+R)

10 ³ = 2.9+2.9+R

1000= 5.8 +R

     R = 1000 -5.8

        = 994.2 ohm

(b).Rate of thermal energy in the resistor R is = i ² R

                                                                  =(1.4x10 ^-3) ² (994.2)

                                                                  = 1.948 J/s