Q.1.A magnetic field of 0.285 T exists in the region enclosed by a solenoid that

Question

Q.1.A magnetic field of 0.285 T exists in the region enclosed by a solenoid that has 329 turns and a diameter of 11.5 cm. Within what period of time must the ?eld be reduced to zero if the average magnitude of the induced emf within the coil during this time interval is to be 13.3 kV? Answer in units of s. Q.2.A strong electromagnet produces a uniform field of 0.98 T over a cross-sectional area of 0.306 m2. A coil having 286 turns with a total resistance of 24.6 ohms is placed around the electromagnet, and the current in the electromagnet is turned off, reaching zero in 21.7 ms.What current is induced in the coil?Answer in units of A.

Explanation / Answer

Firstly, the quantity which is measured in Teslas is magnetic flux density (B). This must be distinguished from magnetic field strength (H) measured in Amps/m Induced voltage can be calculated as N*dF/dt where N is the number of turns and F is the total flux linking the coils. dF/dt is the rate of change of flux with time. If we assume that the flux density is uniform over area A of the coils and that the surface of A is normal to the direction of the B vector, that B changes at a constant rate and that all of the flux links all of the turns, then we can calculate the voltage as:- V = (N*B*pi*r^2)/t where t is the time taken for B to fall to zerothe induced emf is 13.3 kV, it means that the magnetic flux is changed with average rate 4270 Weber/s . total flux at the end of the process is 0. total flux when the magnetic field of 0.285T exists is Flux=B.A.N (B=magnetic filed strength=0.299 T, A=coil's

Related Questions

Navigate

• Browse (All)
• Browse Q
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.