We can calculate the resistance of the radio circuit by using Ohm's law:
![V=IR](https://img.qammunity.org/2019/formulas/physics/college/d5tvvq65gl7etln86jh5pz7v91caixv37n.png)
where
V is the voltage of the circuit
I is the current
R is the resistance
In this circuit,
![V=3.0 V](https://img.qammunity.org/2019/formulas/physics/high-school/nxlu99s06vkr7ekvyfg7n5ihawu58p2eiq.png)
and
![I=2.1 \cdot 10^(-4) A](https://img.qammunity.org/2019/formulas/physics/high-school/iqdk5ums1dhr1439u0wpnopwlxjpzqaewp.png)
. If we rearrange the previous equation and we use these data, we can calculate the resistance of the circuit:
![R= (V)/(I)= (3.0 V)/(2.1 \cdot 10^(-4)A)=1.43 \cdot 10^4 \Omega = 14.3 k\Omega](https://img.qammunity.org/2019/formulas/physics/high-school/l1va7g4gq97n08s5ep0zit8mpzonbneje8.png)