Consider the following statements about a solenoid: 1. The magnetic field strength in a solenoid depends upon the number of turns per unit length in the solenoid 2. The magnetic field strength in a solenoid depends upon the current flowing in the wire of the solenoid 3. The magnetic field strength in a solenoid depends upon the diameter of the solenoid Which of the statements given above are correct?

The magnetic field strength (B) inside an ideal long solenoid is given by the formula B = μ₀nI, where μ₀ is the permeability of free space, 'n' is the number of turns per unit length, and 'I' is the current. Statement 1 is correct because the field is directly proportional to the turn density (n). Statement 2 is correct as the field strength is directly proportional to the electric current flowing through the wire. Statement 3 is incorrect for an ideal or long solenoid; the formula B = μ₀nI shows that the field strength depends only on the turn density and current, and is independent of the solenoid's diameter or cross-sectional area. While the uniformity of the field may relate to the length-to-radius ratio, the magnitude of the internal field in the standard approximation does not depend on the diameter.