Physics

posted by .

A simple motor has N=250 turns of wire on a coil measuring 12 cm \times \, 4 cm. It's resistance is R=10 ohms. The magnetic field is B=1 T.

(a) How much current (in Ampere) in the coil is needed to produce a maximum torque of 40 Nm?

b) What maximum EMF (in Volts) is needed to drive the motor at 50 Hz if the current is constant?

  • Physics -

    (a)
    Torque is
    M=p⒨•B•sinα
    p⒨=NIA
    If M(max) =sin α=1
    M(max)=NIAB,
    I= M(max)/NAB =
    =40/250•0.12•0.04•1=33.3 A
    (b)
    ℰ=-dΦ=-d(NBAsinωt)/dt=
    =-NBAωcosωt
    ℰ(max)=NBAω=2πNBAf=
    =2π•250•1•0.12•0.04•50=377 V

  • Physics -

    Thanks

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Physics

    A coil of wire with 200 circular turns of radius of 3 cm is in a uniform magnetic field along the axis of the coil. the coil has R=40 ohms. At what rate, in Teslas per second, must the magnetic field be changing to induce a current …
  2. physics

    Need help on which formulas I use to solve problems?
  3. Physics

    A 0.35 m2 coil with 50 turns rotates at 5 radians per sec2 in a magnetic field of 0.6 Tesla. What is the value of the rms current in the coil if the coil has the resistance of 3.3 Ù?
  4. Physics

    You have a wire of length L = 2.1 m for making a square coil of a dc motor. The current in the coil is I = 1.8 A, and the magnetic field of the motor has a magnitude of B = 0.32 T. Find the maximum torque exerted on the coil when the …
  5. Physics

    A flat circular coil with 192 turns, a radius of 2.35 x 10-2 m, and a resistance of 0.359 Ù is exposed to an external magnetic field that is directed perpendicular to the plane of the coil. The magnitude of the external magnetic field …
  6. Physics PLEASE HELP!

    A flat circular coil with 97 turns, a radius of 4.04 10-2 m, and a resistance of 0.528 Ω is exposed to an external magnetic field that is directed perpendicular to the plane of the coil. The magnitude of the external magnetic …
  7. physics

    A circular coil with a radius of 25 cm has 20 turns. The coil is oriented perpendicularly to a magnetic field whose initial magnitude is 3.2 T. Suddenly, the magnetic field vanishes in 0.4 s. a. What is the initial magnetic flux in …
  8. physics

    A flat circular coil with 113 turns, a radius of 3.64 10-2 m, and a resistance of 0.524 Ω is exposed to an external magnetic field that is directed perpendicular to the plane of the coil. The magnitude of the external magnetic …
  9. Physics

    A flat circular coil with 193 turns, a radius of 5.50 x 10-2 m, and a resistance of 0.241 Ω is exposed to an external magnetic field that is directed perpendicular to the plane of the coil. The magnitude of the external magnetic …
  10. Physics

    1. A rectangular coil 0.065 m by 0.080 m is positioned so that its cross-sectional area is perpendicular to the direction of a magnetic field. The coil has 66 turns and a total resistance of 7.6 Ω and the field decreases at a rate …

More Similar Questions