Answer:
[tex]t'_{1\2} = 6.6 sec[/tex]
Explanation:
the half life of the given circuit is given by
[tex]t_{1\2} =\tau ln2[/tex]
where [/tex]\tau = RC[/tex]
[tex]t_{1\2} = RCln2[/tex]
Given [tex]t_{1\2} = 3 sec[/tex]
resistance in the circuit is 40 ohm and to extend the half cycle we added new resister of 48 ohm. the net resitance is 40+48 = 88 ohms
now the new half life is
[tex]t'_{1\2} =R'Cln2[/tex]
Divide equation 2 by 1
[tex]\frac{t'_{1\2}}{t_{1\2}} = \frac{R'Cln2}{RCln2} = \frac{R'}{R}[/tex]
[tex]t'_{1\2} = t'_{1\2}\frac{R'}{R}[/tex]
putting all value we get new half life
[tex]t'_{1\2} = 3 * \frac{88}{40} = 6.6 sec[/tex]
[tex]t'_{1\2} = 6.6 sec[/tex]