Advertisements
Advertisements
प्रश्न
A metal disc of radius 30 cm spins at 20 revolution per second about its transverse symmetry axis in a uniform magnetic field of 0.20 T. The field is parallel to the axis of rotation. Calculate
(a) the area swept out per second by the radius of the disc
(b) the flux cut per second by a radius of the disc
(c) the induced emf between the axle and rim of the disc.
Advertisements
उत्तर
Data: R = 0.3 m, f = 20 rps, B = 0.2 T
(a) The area swept out per unit time by a given radius = (the frequency of rotations) x (the area swept out per rotation) = f(πr2)
= (20)(3.142 × 0.09) = 5.656 m2
(b) The time rate at which a given radius cuts magnetic flux
`= ("d"phi_"m")/("dt") = "B f"(pi"r"^2)`
= (0.2)(5.656) = 1.131 Wb/s
(c) The magnitude of the induced emf,
`|e| = ("d"phi_"m")/"dt"` = 1.131 V
APPEARS IN
संबंधित प्रश्न
A 20 cm long conducting rod is set into pure translation with a uniform velocity of 10 cm s−1 perpendicular to its length. A uniform magnetic field of magnitude 0.10 T exists in a direction perpendicular to the plane of motion. (a) Find the average magnetic force on the free electrons of the rod. (b) For what electric field inside the rod, the electric force on a free elctron will balance the magnetic force? How is this electric field created? (c) Find the motional emf between the ends of the rod.
An aircraft of wing span of 50 m flies horizontally in the Earth's magnetic field of 6 x 10-5 T at a speed of 400 m/s. Calculate the emf generated between the tips of the wings of the aircraft.
Mechanical force per unit area of a charged conductor is ______
A cycle wheel of radius 0.6 m is rotated with constant angular velocity of 15 rad/s in a region of magnetic field of 0.2 T which is perpendicular to the plane of the wheel. The e.m.f generated between its center and the rim is, ____________.
Motional e.m.f is the induced e.m.f. ______
An e.m.f is produced in a coil, which is not connected to an external voltage source. This can be due to ______.
- the coil being in a time varying magnetic field.
- the coil moving in a time varying magnetic field.
- the coil moving in a constant magnetic field.
- the coil is stationary in external spatially varying magnetic field, which does not change with time.
A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil. This can be because ______.
- the magnetic field is constant.
- the magnetic field is in the same plane as the circular coil and it may or may not vary.
- the magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably.
- there is a constant magnetic field in the perpendicular (to the plane of the coil) direction.
Find the current in the wire for the configuration shown in figure. Wire PQ has negligible resistance. B, the magnetic field is coming out of the paper. θ is a fixed angle made by PQ travelling smoothly over two conducting parallel wires separated by a distance d.
A magnetic field B = Bo sin ( ωt )`hatk` wire AB slides smoothly over two parallel conductors separated by a distance d (Figure). The wires are in the x-y plane. The wire AB (of length d) has resistance R and the parallel wires have negligible resistance. If AB is moving with velocity v, what is the current in the circuit. What is the force needed to keep the wire moving at constant velocity?
A rod of mass m and resistance R slides smoothly over two parallel perfectly conducting wires kept sloping at an angle θ with respect to the horizontal (Figure). The circuit is closed through a perfect conductor at the top. There is a constant magnetic field B along the vertical direction. If the rod is initially at rest, find the velocity of the rod as a function of time.
Find the current in the sliding rod AB (resistance = R) for the arrangement shown in figure. B is constant and is out of the paper. Parallel wires have no resistance. v is constant. Switch S is closed at time t = 0.
A simple pendulum with a bob of mass m and conducting wire of length L swings under gravity through an angle θ. The component of the earth's magnetic field in the direction perpendicular to the swing is B. Maximum emf induced across the pendulum is ______.
(g = acceleration due to gravity)
Derive an expression for the total emf induced in a conducting rotating rod.
A magnetic flux associated with a coil changes by 0.04 Wb in 0.2 second. The induced emf with coil is ______.
An aircraft of wing span of 60 m flies horizontally in earth’s magnetic field of 6 × 10−5 T at a speed of 500 m/s. Calculate the e.m.f. induced between the tips of the wings of the aircraft.
A wire of length 1 m moving with velocity 8 m/s at right angles to a magnetic field of 2 T. The magnitude of induced emf, between the ends of wire will be ______.
In \[e=Blv\], what does \[l\] represent?
In \[e=Blv\], what does \[v\] represent?
If a rod moves a distance \[dx\] in time \[dt\], what is the change in magnetic flux used in the Faraday's Law derivation?
What is the magnitude of the induced EMF when the Faraday's Law derivation gives \[e=-Blv\]?
What component must the conductor's velocity have for motional EMF?
Which orientation gives maximum motional EMF?
A metallic rod rotates at \[50\,\mathrm{rev/s}\]. What is its angular velocity?
Earth's horizontal magnetic field is \[H_E=0.4\,\mathrm{G}\]. What value of \[B\] is used in tesla?
A wheel has \[10\] metallic spokes, each \[0.5\,\mathrm{m}\] long. It rotates at \[120\,\mathrm{rev/min}\] in a plane normal to Earth's horizontal magnetic field \[H_E=0.4\,\mathrm{G}\]. What is the induced EMF between the axle and rim?
