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# Help Magnetic flux density Please watch

1. I just need help on how to interpret a magnetic flux density against time graph into a emf induced against time graph - I've worked out the emf but how am I meant to know exactly how to plot the emf against time graph? This isn't the standard flux link against time graph... Its from an AQA paper 2003;

"Figure 3 shows how the magnetic flux density, B, through the coil varies with time, t, for one complete oscillation of the magnet. The magnetic flux density through the coil can be assumed to be uniform. Sketch a graph to show how the induced emf in the coil varies during the same time interval."
2. Emf induced is defined as the rate of change of flux linkage. This means the gradient on flux denisty against time graph would be the emf induced at that time. It is quite similar to the gradient on a velocity time graph that represents acceleration at that time. You cna use this to help draw the graph

Hope this helps
3. (Original post by Ladkus)
Emf induced is defined as the rate of change of flux linkage. This means the gradient on flux denisty against time graph would be the emf induced at that time. It is quite similar to the gradient on a velocity time graph that represents acceleration at that time. You cna use this to help draw the graph

Hope this helps
Hi, many thanks for your reply

Ohh so the gradient of this graph (flux density against time) gives me the emf which is also equal to the rate of change of flux linkage? So I could have like 3 graphs on this? One for flux density against time, one for emf against time, and one for flux linkage against time? Its quite confusing to relate them all though :/
4. Flux linkage is just flux density times area times the number of turns in a coil (which are both constant), so flux density is proportional to flux linkage. This means you will get a similar looking graph for both flux linkage and flux density only the values on the flux linkage axis will be multiplied by area and number of turns in the coil if that makes sence.

But what youll find is that when flux linkage is zero on a graph, emf will be max.

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