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Aqa physics electromagnetism

please can someone explain the motor effect and generator effect i dont understand how it works

I have just been revising this lol! The motor effect is when a force is exerted on a current carrying conductor due to being placed in a magnetic field (use Flemings left hand rule)generator effect is when an emf is induced in a conductor due to a changing magnetic field(or due to the conductor moving through field) , use Flemings right hand rule, and basically in the generator effect a force acts on the electrons in the conductor (emf) creating a pd and if connected in a circuit an induced current flows

Reply 2

millbaker

and with motor effect, if u have a coil, the opposite sides of the coil will have current flowing in opposite directions which means the force acting on each side will be in opposite directions which creates a couple and causes it to spin

Reply 3

millbaker

Hope that helped, trying to get my head round it too tbf 😂😭

Reply 4

malkimoo

Original post by millbaker

thanks.. can you explain in more detail, i just starting this topic from scratch and have no idea what going on.. what has magnetic field force and current go to do with each other? x

Reply 5

millbaker

if you have moving charges in a magnetic field (could be current in a wire) a force is exerted on the charges (or electrons in wire) which is perpendicular to the direction of it their movement- this explains the motor effect

Reply 6

millbaker

Also any moving charged particle produces a magnetic field, which means a current carrying wire will have a magnetic field around it the same way a magnet does

Reply 7

malkimoo

so every wire has a magnetic field and force?

Reply 8

millbaker

If it has a current flowing through it!

Reply 9

millbaker

It can’t “have” a force but it has a magnetic field around it

kk tysm x

one more q.. why do the coils turn

Attachment not found

Sorry for how messy the diagrams are but those are the field lines for a straight current carrying wire and then a current carrying coil

Reply 14

malkimoo

could yuo try send attachment again it wont open x

Reply 15

millbaker

Original post by malkimoo

one more q.. why do the coils turn

Imagine a square coil (for simplicity), the current in parallel sides of the coil which are at 90 degrees to field lines will flow in opposite directions meaning each these two sides will have forces in opposite directions, this creates a couple which causes it to spin

Reply 16

millbaker

Original post by malkimoo

could yuo try send attachment again it wont open x

Tbf you can find a better image if u just google field lines for straight current carrying conductor & current carrying coil

kk thx x

You dont really have to understand why what happens happens but you need to know how to explain it in their terms.

Generator effects - When a conductor (usually a wire) moves through a magnetic field and cuts through the field lines ( they often want you to mention this because the generator effect only applies if the wire cuts through the lines), a potential difference is induced in the conductor (basically the conductor gains a potential difference). If it is part of a complete circuit, the potential difference will cause a current to flow. You also need to know how to change the amount of potential difference - if you move the conductor more quickly. the p.d will be higher, if the magnetic field is stronger (they often want you to say a higher magnetic flux density) then the p.d will be higher, if the wire is longer, the p.d will be higher.
You also need to know how AC generators and dynamos work in terms of the generator effect.

Motor effect - If a current is flowing through a wire in a magnetic field and the direction of current is not parallel to the field lines, A force is exerted on the wire causing it to move. The direction in which it moves can be worked out using flemings left hand rule (again read up on this). The size of the exerted force n the wire can be increased by : using a strongee magnet (higher magnetic flux density), longer wire or greatee p.d/current in the wire.