Question

a generator converts mechanical energy to electrical energy. when a coil placed between two magnets rotates, the magnetic lines of force are disturbed. this induces a current in the coil. the image below shows a generator.
what could be done to make the lamp less bright?
○a. increase the strength of the magnets
○b. use a lamp that lights up with a lower current
○c. turn the coil faster
○d. move the magnets farther from the coil

Explanation:

• Option A: Increasing magnet strength increases magnetic flux, inducing more current (lamp brighter).
• Option B: Using a lamp with lower current requirement would make it brighter if same current is induced.
• Option C: Faster coil rotation increases rate of flux change, inducing more current (lamp brighter).
• Option D: Moving magnets farther reduces magnetic flux through coil. By Faraday's law (\(\mathcal{E}=-N\frac{\Delta\Phi}{\Delta t}\)), induced emf (and thus current) decreases, making lamp less bright.

Answer:

D. move the magnets farther from the coil