Question

The heating coils in a hair dryer are 0.95 cm in diameter, have a combined length of 0.75 m, and a total of 400 turns Part (a) What is their total self-inductance, assuming they act like a single solenoid, in H? Part (b) How much energy is stored in them when 6.25 A flows in ? Part (c) What average emf in mV opposes shutting them off if this is done in 5.00 ms (one-fourth of a cycle for 50 Hz AC

Answer 1

The self-inductance of the solenoid is, I HON²A _ 41° (zrº) _(47x10-?Tm/A)(400)? 7(0.475x10-2 m)? 0.75m =0.019x10 'H =0.019 mH

The energy stored in the solenoid is, = -(0.019x10ʻH)(6.25 A) = 3.71x10+J c) The average emf induced in the solenoid is, E=L41 (0.019x10-²H)(6.25A) 5.0x10-s = 23.75x10v =23.75mV