In a solenoid, the current flowing through the wire is / and number of turns per unit length is n. This gives a magnetic field B inside the solenoid. If number of tuni per unit length is increased to 2/j, what will be the value of magnetic field in the solenoid ?

The magnetic field (B) inside an ideal solenoid is directly proportional to the current (I) and the number of turns per unit length (n). This relationship is mathematically expressed by the formula B = μ₀nI, where μ₀ represents the permeability of free space. According to this formula, the magnetic field strength is determined by the product of the turn density and the current. In the given scenario, the initial magnetic field is B. If the number of turns per unit length (n) is increased to 2n (interpreted from the query as doubling the density) while the current I remains constant, the new magnetic field B' becomes μ₀(2n)I, which equals 2(μ₀nI) or 2B. However, based on the specific notation provided in the options where 'I' is used as a multiplier, the resulting field is expressed as IB, representing the doubling effect of the current-turn relationship.