Question

please do both of them asap

4) A wire is carrying a current of I and it is placed in a magnetic field of B, the force on the wire is zero if: A) The length of wire is infinite. B) If there is a non-zero angle between magnetic field B and current I. C) The direction of the current and magnetic field are perpendicular. D) The current and magnetic field are parallel. E) There is a 90 degree angle between current direction and magnetic field direction. 5) The force between two parallel wires carrying electric current is repulsive when: A) The magnitude of the current of both wires are the same. B) The direction of current in wires are opposite. C) One of the wires is carrying no current. D) The direction of the currents in wires are the same. E) Wires carrying different current values.

Answer 1

a force acting on a current carrying wine in magnetic field B T! Tall f.= I ex B I sin I current the wire through length off wire magnetic field angle between I and B can be zero if yli) if yli) I co l B o con رأ 0 or = 0 cir civ or Ŝ = angle between direction of I and i co Thus option D is correct option. (5 tu I, 1 I 7 1 (c expression first we need to derive for magnetic field due to current paint. Camping wine at some

I بان carrying a rate We IE Consider one of the wire current I, and have to calculate magnetic field due to this wire at any point P. for this amperical loop through point p centred at the wire drawing

Applying Ampera Ampere's laws - so de permeability of_free space Mo lenc Mas Tenc Current enclosed in the lo the curling of finger magnetic o. de length element of the If | stretch my thumb in the direction current and curl my fingers along loop then the direction of field. Thus angle between B and di and B at point e point into the of paper (incword) fleillail coso Moreno coso = coso 1 fiat , مال {lenc Bfde Mali B (total length of loop) = Mol 8_€ 21 ) = Mol = Mo I, (inward) 2xr
Summary: first I derived expression for the magnetic field due to current carrying wire then I calculated force acting between two wires.