3. You are given a bar magnet, but the poles are not labeled. Using which of the

Question

3. You are given a bar magnet, but the poles are not labeled. Using which of the following items can you determine which endis a north pole and which is a south pole? (a) a voltmeter (b) a bottle of iron particles (c) a charged rubber rod (d) a compass (e) a steel rod 4. Consider the two rectangular areas shown with a point P located at the midpoint between the two areas. The rectangular area on the left contains a bar magnet with the south pole near point P. The rectangle on the right is initially empty. How will the magnetic field at P change, if at all, when a second bar magnet is placed on the right rectangle with its north pole near point P? (a) The magnetic field at P will be zero tesla. (b) The direction of the magnetic field will not change, but its magnitude will decrease. (c) The direction of the magnetic field will not change, but its magnitude will incre (d) The direction of the magnetic field will change and its magnitude will increase. (e) The direction of the magnetic field will change and its magnitude will decrease. ase. 5. A rigid, conductive loop is falling through a uniform magnetic field that is perpendicular to the plane of the loop. Initially, th loop is completely within the field, but then it falls into a region where no magnetic field is present. Which one of the following quantities varies during the fall? (a) the magnetic field penetrating the loop (c) the area of the loop penetrated by the magnetic field (b) the magnetic flux (d) the current in the loop (e) all of the above 6. An inductor is connected to an alternating current power supply. If the inductor is replaced with another that has a small inductance, what is the effect on the rms current in the circuit and the inductive reactance? (a) The rms current will increase as the inductive e reactance decreases. (b) The rms current will decrease as the inductive reactance increases (c) The rms current will increase as the inductive reactance increases. (d) The rms current will remain at its initial value as the inductive reactance decreases. (e) The rms current will decrease as the inductive reactance decreases.

Explanation / Answer

3. Only compass could be used for classifucaclas of poles .. because to determine poles of bar magnet we need some reference poles these are indicated on compass

4. Magnetic field lines starts from N ends to S ,now when another bar magnet is placed with P near North Pole, there it will form field due to two magnetic dipoles so field will increase but direction will remain same

5. Here all things will vary , since loop goes from one region of magnetic field to regoin where field is absent so field penetrating lopp will change ,due to this flux through loop will change ,due to change in flux emf generates and so current.

6. RMS current will remain same ,but inductive reactance which is proportional to inductance will decrease.

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