______ is a vertical line in a table.

Q. A charged particle is whirled in a horizontal circle on a frictionless table by attaching it to a string fixed at one point. If a magnetic field is switched on in the vertical direction, the tension in the string

Q. A very long magnet is held vertically with its south pole on a table. A single neutral point is located on the table on :

Q. When the north pole of a magnet is kept vertically on a table, then

Q. A fluorescent tube which is equivalent to a line source of $100$ candela per meter is hung horizontally $5$ meters above the table. The illuminance at a point vertically below the tube will be