a] What is a solenoid ? Draw the patterns of magnetic field lines of a solenoid through which a steady current flows. What does the pattern of field lines the solenoid indicate?
b] Write one use of a solenoid .

Explanation

a] A coil of insulated copper wire wound in the form of a cylinder is a solenoid. When current is passed through a solenoid, it produces magnetic field lines like a bar magnet. The pattern of magnetic field lines of a solenoid is shown in the figure.
Inside the solenoid, field lines are parallel to each other This indicates that the magnetic field is uniform .
b] Solenoids are used in hotel door-locks, are conditioners, storage hard-disks, speakers, microphones, power plants, cars, etc.