Question

An inductor coil,a capacitor and an alternating source of virtual value 36 V are connected in series.When the frequency of the source is varied, a maximum virtual current 4 A is observed. If this inductor coil is connected to a battery of emf 18V and internal resistance$9\Omega$, the current in the circuit will be:

• A. 1 A
• B. 2 A
• C. 3 A
• D. none of these

Answer 1

The correct option is A 1 A

Given that,

e. m. f = $18V$

$E_{rms}=36V$

Internal resistance $r=9\Omega$

Current $I_{rms}=4A$

Now, the external resistance is

We know that,

$R=\frac{E_{rms}}{I_{rms}}$

$R=\frac{36}{4}$

$R=9\Omega$

When the inductor coil is connected to a 18 V battery with 9 $\Omega$ internal resistance:

Now, net resistance is

$R_{net}=R+r$

$R_{net}=9+9$

$R_{net}=18\Omega$

Now, the current is

$I=\frac{e.m.f}{R_{net}}$

$I=\frac{18}{18}$

$I=1A$

Hence, the current is $1A$ in the circuit