Why does Lenz's law have a minus sign?
The minus sign shows that the direction of induced current always opposes the change that created it. So when certain metals are cropped through say a copper tube they slow down. Show video of Lenz's law in action. The current is induced in the opposite direction to ensure that energy is conserved and not created from nothing.
When pushing a magnet into a coil, if you push the North pole towards the coil first then a North pole is induced in the coil to repel the magnet. The magnet is slowed down and repelled by the coil, the kinetic energy here is dissipated as heat.
JJ
Related Physics A Level answers
All answers ▸A source of green laser light has a wavelength of 560nm, what is its frequency? Give your answer to an appropriate number of significant figures and using the correct units.
The tip of each prong of a tuning fork emitting a note of 320Hz vibrates in SHM with an amplitude of 0.50mm. What is the speed of each tip when its displacement is zero?
Electrons moving in a beam have the same de Broglie wavelength as protons in a separate beam moving at a speed of 2.8 × 10^4 m/s . What is the speed of the electrons?
A linear accelerator (LINAC) is used to accelerate protons at CERN before they are injected into the Large Hadron Collider. Explain with the aid of a diagram how the proton is accelerated by the LINAC.