Question

If other factors remain constant, which of the following combinations of number of turns per 20 cm

and electric current respectively in a solenoid produce the weakest electromagnet?

(1) 500 turns & 3 A (2) 700 turns & 2 A

(3) 200 turns & 5 A (4) 300 turns & 4 A


Hurry...... ​

Answer 1

Answer:

(3) 200 turns and 5A

Explanation:

Magnetic field in axis due to ideal solenoid =uni/2

where u is magnetic permeability, n is number of turns and i is the current flowing.

So, Magnetic field is directly proportional to ni.

Product of ni is lowest in (3).