Question

0 science magnetic effects of electric current notes

Answer 1

Introduction


→ Magnet is any substance that attracts iron or iron-like substances.

→ An electric current-carrying wire behaves like a magnet.

→ Electromagnets and electric motors involve the magnetic effect of electric current, and electric generators involve the electric effect of moving magnets.

→ Compass needle get deflected on passing an electric current through a metallic conductor.




Properties of Magnet

(i) Every magnet has two poles i.e. North and South.




(ii) Like poles repel each other.

(iii) Unlike poles attract each other.

(iv) A freely suspended bar magnet aligns itself in nearly north-south direction, with its north pole towards north direction.

Characteristics of Field Lines




→ Field lines arise from North pole and end into South pole of the magnet.

→ Field lines are closed curves.

→ Field lines are closer in stronger magnetic field.

→ Field lines never intersect each other as for two lines to intersect, there must be two north directions at a point, which is not possible.

→ Direction of field lines inside a magnet is from South to North.

→ The relative strength of magnetic field is shown by degree of closeness of field
lines.

Magnetic Field of a Bar Magnet

→ H. C. Oersted was the first person to state that electric current has magnetic field.




Right Hand Thumb Rule





→ Imagine you are holding a current carrying straight conductor in your right hand such

that the thumb is pointing towards the direction of current.


→ Then the fingers wrapped around the conductor give the direction of magnetic field.


Magnetic Field due to Current through a Straight Conductor


→ It can be represented by concentric circles at every point on conductor.


→ Direction can be given by right hand thumb rule or compass.


→ Circles are closer near the conductor.


→ Magnetic field ∝ Strength of current.


→ Magnetic field ∝ 1/Distance from conductor