(A) (i) Draw the pattern of the magnetic field lines for the two parallel straight conductors carrying…
(A) (i) Draw the pattern of the magnetic field lines for the two parallel straight conductors carrying current of same magnitude 'I' in opposite directions as shown. Show the direction of magnetic field at a point O which is equidistant from the two conductors. (Consider that the conductors are inserted normal to the plane of a rectangular cardboard.)
(ii) In our houses we receive A.C. electric power of 220 V. In electric iron or electric heater cables having three wires with insulation of three different colours - red, black and green are used to draw current from the mains.
(a) What are these three different wires called? Name them colourwise.
(b) What is the potential difference between the red wire and the black wire?
(c) What is the role of the wire with green insulation in case of accidental leakage of electric current to the metallic body of an electrical appliance?
Solution
(A)
(i)
[Diagram: magnetic field pattern of two parallel current-carrying wires, concentric circles around each wire with a straight line between them]
Correct Pattern
Correct direction
(ii) (a)
red wire : Live wire
black wire : Neutral wire
green wire : Earth wire
(b) 220 V
(c) This is used as a safety measure. It ensures that any leakage of the current to the metallic body of the appliance keeps its potential to that of the earth and the user may not get a severe electric shock.
