What must the charge (sign and magnitude) of a particle of mass 1.43 g be for it to remain stationary when placed in a downward-directed electric field of magnitude 700 N/C ? Use 9.80 m/s2 for the magnitude of the free-fall acceleration.

the sign and magnitude of the charge is - 2 x 10⁻⁵ C.

Explanation:

Given;

mass of the particle, m = 1.43 g = 0.00143 kg

electric field experienced by the particle, E = 700 N/C

The force experienced by the particle is calculated as;

F = mg = EQ

Where;

Q is the magnitude of the charge

The force must be upward in opposite direction to the electric field. Since the force and the electric field are in opposite direction, the charge must be negative.

Therefore, the sign and magnitude of the charge is - 2 x 10⁻⁵ C.

unlike poles attract

the part of the wave he is travelling on is the crest