Magnetic Field

Q.

What is H in the magnetic field?

Q.

A bar magnet is immersed in a heap of iron filings and pulled out. The amount of iron filing clinging to the

1. The North Pole is almost equal to the South Pole.

2. The north pole is much more than the South Pole.

3. The north pole is much less than the South Pole.

4. The magnet will be the same all along its length.

Q. Three infinitely long current carrying wires are placed at the vertices of an equilateral triangle of side a. Current carrying by each wire is I. They are placed along the line perpendicular to plane of triangle. Find the magnetic field at centroid of triangle ?

Q. The equation for a magnetic field line (in polar coordinates) in 2 dimensions is given by ___?

1. $\frac{B_r}{B_{\Theta }}=\frac{dr}{d\Theta }$
2. $\frac{B_r}{B_{\Theta }}=\frac{dr}{rd\Theta }$
3. $B_r\times B_{\Theta }=dr\times d\Theta$
4. $B_r\times B_{\Theta }=\frac{dr}{d\Theta }$

Q. Consider an iron nail with ends $A$ and $B$. A bar magnet is brought near end $A$ of the iron nail with its North Pole facing the end $A$. Choose the correct statement.

1. The iron nail becomes a temporary magnet with end $B$ as its South Pole.
2. The iron nail becomes a temporary magnet with end $A$ as its South Pole.
3. The iron nail becomes a permanent magnet with end $A$ as its North Pole.
4. The iron nail becomes a permanent magnet with end $B$ as its North Pole.

Q. What is the difference between magnetic meridian, magnetic equator and equatorial meridian of apermanent bar magnet?

Q.

When a magnet is kept on a table and a compass is taken close to it, it points in a certain direction at every point near the magnet. When the points are joined, we obtain certain lines. Choose the correct statement(s) regarding the lines
1. The closer they are, the stronger the magnet.
2. They are imaginary lines which have a particular direction.

1. Only 1
2. Only 2
3. Both 1 and 2
4. Neither 1 nor 2

Q.

Given below are two statements which of the statement is/are true?

Statement (A):- When the south pole of a magnet points towards the geographical north pole, the null points are along the equatorial line.

Statement (B):- At the null point, the earths magnetic field is zero.

1. A is true B is false

2. Both A and B are false

3. A is false B is true

4. Both A and B are true

Q. Statement 1: Permanent magnet is used in commerical electric motors.
Statement 2: Number of turns of conducting wire is kept low.
Select the correct option from below.

1. Both the statements are true.
2. Only statement 2 is true
3. Only statement 1 is true
4. Both the statements are wrong.

Q.

Electric current were induced in closed coils when subjected to change in magnetic fields .What do we meanby closed coils.

Q. What would be the position of black particle, if blue particle completes half a cycle?

1. Crest
2. Trough
3. Mean
4. Cannot tell

Q.

If at the centre of the given solenoid, an iron ring is placed coaxially .Then identify in which direction will the magnetised iron ring's north-pole will be?

1. 1

2. 2

3. There won't be any north as the magnetic field lines will be circular in anti-clockwise direction and inside the magnet

4. There won't be any north as the magnetic field lines will be circular in clockwise direction inside the magnet