Magnetism — Physics STD 12 Science — Question

Consider the points lying on a straight line joining two fixed opposite charges. Between the charges there is (a) No point where electric field is zero(b) Only one point where potential is zero(c) Only one point where electric field is zero(d) a, b

Which metal is used to make ferromagnets ?

Assertion  :  A transistor amplifier in common emitter configuration has a low input impedence.
Reason      : The base to emitter region is forward biased.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

The time period of oscillation of a magnet in a vibration magnetometer is 1.5 seconds. The time period of oscillation of another magnet similar in size, shape and mass but having one-fourth magnetic moment than that of first magnet, oscillating at same place will be(a) 0.75 sec(b) 1.5 sec(c) 3 sec  (d) 6 sec

The graph shows the variation of magnetic field (B)with distance (r) from a long current carrying wire is-

There is some liquid in a closed bottle. The amount of liquid is continuously decreasing. The vapour in the remaining part:

1. Must be saturated.
2. Must be unsaturated.
3. May be saturated.
4. There will be no vapour.

Magnetic needle can remain safe in:

In potentiometer a balance point is obtained, when: