A straight wire carrying a 300 a current is placed in a...

A straight wire carrying a 3.00-A current is placed in a uniform magnetic field of magnitude 0.280 T directed perpendicular to the wire. (a) Find the magnitude of the magnetic force on a section of the wire having a length of 14.0 cm. (b) Explain why you can’t determine the direction of the magnetic force from the information given in the problem.

Transcript

00:01 So in this question, we are given some information and for that i'm first of all dividing my screen into four parts.

00:08 So on two, three, four.

00:12 So i'm doing it because there is a reason to it.

00:15 So, okay.

00:16 So now let us try to solve the problem which we have at hand.

00:20 So now we are given that there is a wire.

00:24 There is a wire which is carrying some current and it is placed in a magnetic field which is perpendicular.

00:29 So now i'm taking different different cases.

00:34 So i have kept the wire like this here also, here also, here also.

00:37 Now it is given that there is a magnetic field which is perpendicular to the wire.

00:42 So there are many cases, right? so for example, if you take the magnetic field like this, then also it is perpendicular to the wire.

00:54 This is magnetic field.

00:56 If the magnetic field is acting in this direction, then also it is perpendicular to the length of wire.

01:02 If the magnetic field is entering into the plane of paper, then also the magnetic field is perpendicular to the current.

01:10 If the magnetic field is coming towards you is coming out of the plane of the paper, then also the current is perpendicular to the magnetic field.

01:23 So now in all the cases, as we know, amount of magnetic force, magnitude, we know that it is a cross product of i.

01:32 L cross p.

01:33 This is a net force vector so from here if i'm interested in the magnitude of the force i would say it is i l b sine theta where theta is the angle between magnetic field and current so which is definitely 90 so magnetic force in all the cases will come out to be i lb only here also it would be i lb because angle is 90 there's no doubt about it here also the force is i lb here also the force is i .lb only.

02:02 The magnetic force won't change magnitude -wise.

02:06 It is just the direction which will change.

02:09 So the magnitude of force we can find first of all.

02:13 So to answer this, we can find for any case and then we can put the value.

02:18 So the value of current is given to us, basically.

02:20 It is three ampiers.

02:21 It is given to us.

02:22 So i means three emperors.

02:25 Okay.

02:26 So length is given to us, which is 14 centimeters.

02:29 So 14 into 10 .000 to power minus 2...