A student fixes a sheet of white paper on a drawing board using some adhesive materials. She places a bar…
A student fixes a sheet of white paper on a drawing board using some adhesive materials. She places a bar magnet in the centre of it and sprinkles some iron filings uniformly around the bar magnet using a salt-sprinkler. On tapping the board gently, she observes that the iron filings have arranged themselves in a particular pattern.
(a) Draw a diagram to show this pattern of iron filings. [1]
(b) Draw the magnetic field lines of a bar magnet showing the poles of the bar magnet as well as the direction of the magnetic field lines. [1]
(c) (i) How is the direction of magnetic field at a point determined using the field lines ? Why do two magnetic field lines not cross each other ? [2]
Solution
(a) [diagram of magnetic field lines around a bar magnet, from N pole to S pole]
(b) [diagram of closed-loop magnetic field lines around a bar magnet, N to S]
(c) i) By placing a compass needle on magnetic field lines, direction of north pole will give direction of magnetic field.
If they cross or intersect , it means that at point of intersection the compass needle would point into two directions, which is not possible. /
If they cross or intersect, it means that at point of intersection there will be direction of two resultant fields which is not possible.