Magnetic Effects of Current Test Online MCQs

1. Electron of mass m and charge q is travelling with a speed along a circular path of radius r at right angles to a uniform magnetic field of intensity B. If the speed of the electron is doubled and the magnetic field is halved the resulting path would have a radius

2. An electron is travelling along the x-direction. It encounters a magnetic field in the y-direction. Its subsequent motion will be:

3. In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio (charge on the ion/mass of the ion) will be proportional to

4. Two identical conductors of copper and aluminum are placed in an identical electric field. What is the magnitude of induced charge in the aluminum?

5. Two parallel beams of positrons moving in the same direction will:

6. Two concentric coils each of radius equal to 2π cm are placed at right angles to each other. 3 ampere and 4 ampere are the currents flowing in each coil respectively. The magnetic induction in Weber/m² at the center of the coils will be (μ₀ = 4π x 10⁻⁷ Wb/A.m)

7. The magnetic moment of current (I) carrying circular coil of radius (r) and number of turns (n) varies as:

8. The cyclotron frequency of an electrons gyrating in a magnetic field of 1 T is approximately:

9. The magnetic flux through a circuit carrying a current of 2.0 A is 0.8 Weber. If the current reduces to 1.5 A in 0.1 s, the induced emf be:

10. What should be amount of current through the rings of radius of 5 cm so that field at the center equal to the earth’s magnetic field of 7 x 10⁻⁵ Wb/ m², is

11. An electron moving with kinetic energy 6.6 x 10⁻¹⁴ J enters in a magnetic field of 4 x 10⁻³ T at right angles to it. The radius of its circular path will be nearest to:

12. A circular coil of radius R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance r from the center of the coil, such that r > > R, varies as

13. A long straight wire of radius a carries a steady current i. The current is uniformly distributed across its cross section. The ratio of the magnetic field at a/2 and 2a is

14. A coil of copper having 1000 turns is placed in a magnetic field (B=4 x 10⁻⁵) perpendicular to its axis. The cross sectional area of eh coil is 0.05 m². If it turns through 180° in 0.01 second, then the e.m.f. induced in the coil will be:

15. The magnetic field due to a square loop of side a carrying a current I at its center is