Q.1. When will a current carrying wire not be able to deflect a magnetic needle placed in vicin-
ity?
Q.2. A student dropped a bar magnet into the cylindrical cavity of a solenoid, such that the mag-
net fallls freely How will the acceleration due to gravity be affected during the fall through
cavity?
Q.3. If a current through a circular loop. placed on a table flows clockwise, what will be the
direction of magnetic field?
(1)
Q.4. How will you determine the direction of magnetic field at a point near a magnet or current
carrying conductor?
Q.5. What will happen when, a bunch of protons and electrons are made to pass through a mag-
netic field perpendicular to the direction of motion? State reason for your answer. (2)
Q.6. A current carrying aluminium rod placed in a magnetic field experiences a force upwards
when the current through the rod flows eastward. Determine the directon of magnetic field
Also state the direction in which the rod should be moved to produce induced current in the
same durection
0.7. How will the force experienced by a conductor affected when the conductor is stretched to
twice of its length
Q.s. State the factors on which strength of the magnetic field produced by straight wire carrying
current depends. Also state the way it depends on these factors.
Q.9. How will the arrangement of iron filings on a cardboard through which a wire carrying
current passes at night angle change when the direction of current is reversed? State reason
for your answer
Q.10. Explan with diagram an activity to illustrate that induced current can be produced by
changmg magnetic field around a conductor
Q.11. What is commutator? What serves the purpose of commulator in a DC motor? Why is
commulator required im DC motor?
Q.12. State the reasons that results in overloading of domestic circuits? What could be the effect
of overloading for a prolonged interval of time? How can this effect be avoided?
Answers
Answer: A convenient way of finding the direction of magnetic field associated with a current-carrying conductor is using the Right hand thumb rule.
Imagine that we are holding a current-carrying straight conductor in our right hand such that the thumb points towards the direction of current. Then our fingers will wrap around the conductor in the direction of the field lines of the magnetic field. This is known as the right-hand thumb rule.
Let us consider that a current through a horizontal power line flows in east to west direction. Applying the right-hand thumb rule, the direction of magnetic field at a point below the wire is from north to south. The direction of magnetic field at a point directly above the wire is from south to north.
Thus, when a magnetic compass is brought below the current carrying wire the compass needle show deflection in the north-south direction.
Explanation: