A long solenoid is formed by winding 70 turns cm$$^{-1}$$. If 2.0 A current flows, then the magnetic field produced inside the solenoid is _____.
($$\mu_0 = 4\pi \times 10^{-7}$$ T m A$$^{-1}$$)

The magnetic field inside a solenoid is given by:

$$B = \mu_0 n I$$

where $$n$$ is the number of turns per unit length and $$I$$ is the current.

Given: $$n = 70$$ turns/cm $$= 7000$$ turns/m, $$I = 2.0$$ A, $$\mu_0 = 4\pi \times 10^{-7}$$ T m A$$^{-1}$$.

$$B = 4\pi \times 10^{-7} \times 7000 \times 2.0$$

$$= 4\pi \times 14000 \times 10^{-7}$$

$$= 56000\pi \times 10^{-7}$$

$$= 56\pi \times 10^{-4}$$

$$= 56 \times 3.14159 \times 10^{-4}$$

$$\approx 175.93 \times 10^{-4}$$

$$\approx 176 \times 10^{-4}$$ T

The correct answer is Option 2: $$176 \times 10^{-4}$$ T.