Electrostatics — Physics STD 12 Science — Question

Two similar spheres having +q  and -q charge are kept at a certain distance. F force acts between the two. If in the middle of two spheres, another similar sphere having +q charge is kept, then it experience a force in magnitude and direction as

(a) Zero having no direction	(b) 8F towards +q  charge
(c) 8F towards -q  charge	(d) 4F towards +q  charge

A bulb has specification of one kilowatt and 250 volts, the resistance of bulb is

(a) 125 W

(b) 62.5 W

(c) 0.25 W

(d) 625 W

To use a transistor as an amplifier, emitter-base junction is kept in ...X... and base-collector junction is kept in ...Y... Here, X and Y refer to:

If a charged particle kept at rest experiences an electromagnetic force:

1. The electric field must not be zero.
2. The magnetic field must not be zero.
3. The electric field may or may not be zero.
4. The magnetic field may or may not be zero.

If a diamagnetic substance is brought near north or south pole of a bar magnet, it is:

Which one of the following is a safe place during lightning?

An electron revolves 6 × 10¹⁵ times/sec in circular loop.  The current in the loop is

(a) 0.96 mA

(b) 0.96 m A

(c) 28.8 A

(d) None of these

Pick the correct options.