A long, air-cored solenoid is used in a school laboratory demonstration. (i) What is…
PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A long, air-cored solenoid is used in a school laboratory demonstration.
(i) What is meant by the term "turns per unit length" of a solenoid?
(ii) Keeping the total number of turns and the length of the solenoid unchanged, explain qualitatively how the magnetic field inside the solenoid will change when the current through it is doubled.
(iii) Keeping the current unchanged, explain qualitatively how the magnetic field inside the solenoid will change when the number of turns is doubled while the length remains the same.
(iv) Give one reason why the magnetic field at points well inside a long solenoid is considered practically uniform along its axis.