Physics

A circular antenna of area 3 m2 is installed at a place in Madurai. The plane of the area of antenna is inclined at 47º with the direction of Earth’s magnetic field. If the magnitude of Earth’s field at that place is 40773.9 nT find the magnetic flux linked with the antenna.

• 89.47 $\mu WB$

• 72 $\mu WB$

• 60.98 $\mu WB$

• 100.54 $\mu WB$

A closed coil of 40 turns and of area 200 cm2, is rotated in a magnetic field of flux density 2 Wb m-2. It rotates from a position where its plane makes an angle of 30º with the field to a position perpendicular to the field in a time 0.2 sec. Find the magnitude of the emf induced in the coil due to its rotation.

• 15V

• 10V

• 4V

• 2V

The magnetic flux of the initial coil has 200 loops changes by 0.06 Wb in 0.4 seconds. The magnetic flux of the final coil has 0.08 Wb in 0.2 seconds. If a number of loops of the final coils are substituted with the half number of the first coil’s loops, determine the ratio of the induced emf of the initial loops and the final loops.

• 3:7

• 4:5

• 1:2

• 3:4

If the current i flowing in the straight conducting wire as shown in the figure decreases, find out the direction of induced current in the metallic square loop placed near it.

• Clockwise

• Anti-Clockwise

A copper disc 20 cm in diameter rotates with an angular velocity of 60 rev s^-1 about its axis. The disc is placed in a magnetic field of induction 0.2 T acting parallel to the axis of rotation of the disc. Calculate the magnitude of the e.m.f. induced between the axis of rotation and the rim of the disc.

• 0.102 V

• 0.405 V

• 0.377 V

• 0.734 V

What is a magnetic field?

• a region of space where a mass experiences a force.

• the physical property of matter that causes it to experience electromagentic force.

• force of attraction between two magnets.

• a region of space where a magnetic pole experiences a force.

What is the SI unit of tesla?

• kg.s^-2.A^-1

• N.m^1.A^-1

• N.m^-1.kg^-1

• kg.m^-1.A^-1

A 4 m by 5 m rectangle of wire is exposed to a magnetic field of 5 T. The magnet field lines and the normal to the plane of the rectangle make an angle of 60 degrees. What is the magnetic flux of the rectangle?

• 35Wb

• 100Wb

• 50Wb

• 10Wb

A rectangular coil of wire has sides of lengths 40 cm and 50 cm. The coil contains 55 turns. The coil is placed into a magnetic flux density of 0.35 T. All the sides of the turns of the coil are perpendicular to the direction of the field. What is the magnetic flux of the coil?

• 3.85Wb

• 4.55Wb

• 5.35Wb

• 2.00Wb

An automobile with a radio antenna 2.0 m long travels at 120.0 km/h in a location where the Earth’s horizontal magnetic field is 5.5 × 10⁻⁵ T. What is the maximum possible emf induced in the antenna due to this motion?

• 4.23×10^-3v

• 1.79×10^-3v

• 2.76×10^-3v

• 3.67×10^-3v