PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
For 0 ≤ t ≤ 6 s, the magnetic flux through a coil is given by
Φ(t)=0.05t2−0.30t(Wb).
The coil has 100 turns and resistance 2 Ω.
(i) Derive an expression for the induced emf ε(t) as a function of time.
(ii) Determine the instants within the interval 0–6 s when the induced emf is zero.
(iii) Obtain an expression for the instantaneous power dissipated in the coil and hence calculate the total thermal energy produced in the coil between t = 0 s and t = 6 s.
(iv) Sketch on the same set of axes the graphs of Φ(t) and ε(t) for 0 ≤ t ≤ 6 s, indicating critical points obtained above.