Tag: physics

When a charged object comes in contact with the Earth, the charges flow into the Earth and the body gets discharged. This process is called earthing.

According to the Biot Savart's law, a current carrying conductor produces a magnetic field in its surroundings. This will cause the helix to oscillate across a mean position.

A charged particle produces an electric field around it independent of its motion. But when it is at rest, it doesn't produce a magnetic field. 

Answer is D.

A solenoid is an electromagnet. That is, it acts as a bar magnet only when electricity is passed through it. Its purpose is to generate a controlled magnetic field. 
A solenoid is a coil of insulated or enameled wire wound on a rod shaped form made of solid iron solid steel or powdered iron.

In his experiment Oersted observed that the deflection of the needle compass changed according to the direction of the current and also as the current in the wire increased, the deflection of the needle increased. Thus he inferred that the strength and direction of the magnetic field depends on the magnitude and direction of current.

Heating effect and lighting effect does not depend on the direction of current.

Oersted conducted an experiment to study the magnetic effect of electric current. In this experiment he observed the deflections of a compass needle placed in close proximity of an electric wire carrying current. He observed that in the absence of current the needle came to rest in Earths North-south direction under the influence of Earths magnetic field. However, when the needle was kept in close proximity of an electric wire carrying current it showed deflections in the east and west direction depending on the direction of current. Thus, indicating that the strength and direction of the magnetic field depends on the magnitude and direction of the current.

In his experiment Oersted observed that as the current in the wire increased, the deflection of the needle also increased, indicating that they are directly proportional.