3:08 Shouldn't we use EMF= -L* di/dt because that was what the earlier formula said? Are we even talking about back EMF in the question? Also I didn't understand the question in 5:11. Could you please explain?
The formula for electromotive force (EMF) is indeed EMF=−L di/dt The negative sign reflects Lenz's law, which indicates that the induced EMF opposes the change in current. However, when discussing the magnitude of the EMF, the absolute value should be taken, which is why I omitted the negative sign in earlier discussions. To clarify, absolute value symbols (∣EMF∣) should have been placed around the EMF symbol to indicate this explicitly. At 5:11 in the video, the question presents a positive EMF and asks how the current is changing. A positive EMF implies that the current must either be: Slowing down in the rightward direction, or Speeding up in the leftward direction. In either of these scenarios, the current is changing in a way that requires a positive rightward EMF to attempt to maintain its flux. This aligns with the principle that the inductor generates an EMF to oppose the change in flux, as dictated by Lenz's law.
Terrific!
Thanks for your comment it was fantastic!
3:08 Shouldn't we use EMF= -L* di/dt because that was what the earlier formula said?
Are we even talking about back EMF in the question?
Also I didn't understand the question in 5:11. Could you please explain?
The formula for electromotive force (EMF) is indeed EMF=−L di/dt
The negative sign reflects Lenz's law, which indicates that the induced EMF opposes the change in current. However, when discussing the magnitude of the EMF, the absolute value should be taken, which is why I omitted the negative sign in earlier discussions. To clarify, absolute value symbols (∣EMF∣) should have been placed around the EMF symbol to indicate this explicitly.
At 5:11 in the video, the question presents a positive EMF and asks how the current is changing. A positive EMF implies that the current must either be:
Slowing down in the rightward direction, or
Speeding up in the leftward direction.
In either of these scenarios, the current is changing in a way that requires a positive rightward EMF to attempt to maintain its flux. This aligns with the principle that the inductor generates an EMF to oppose the change in flux, as dictated by Lenz's law.