Physics - Study Mode

[#1001] A solid ball of metal has a spherical cavity inside it. When the ball is heated the volume of the cavity will
Correct Answer

(A) Increase

Explanation

Solution: The metal ball can be considered to be made up of several layers of thinner ones. On heating each of these layers will increase in radius. As the inner most layer also increases its radius, the volume inside it i.e, the volume of the hollow portion will also increase.

[#1002] Electromagnet is constructed with which of the following ?
Correct Answer

(B) Soft Iron

Explanation

Solution: An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off. It is made of soft iron since it has the property of losing its magnetism very quickly. The soft iron core of the electromagnet makes the magnetic field stronger.

[#1003] When number of turns in a coil is trippled, without any change in the length of coil, its self inductance becomes?
Correct Answer

(A) Nine times

Explanation

Solution: L = inductance is proportional to the number of turns per unit length. So self inductance becomes three times. if turns in a coil is trippled, self inductance become nine times.

[#1004] Fleming's right hand rule is used to find the direction of the
Correct Answer

(C) Induced current

Explanation

Solution: Fleming's right-hand rule (for generators) shows the direction of induced current when a conductor attached to a circuit moves in a magnetic field. It can be used to determine the direction of current in a generator's windings.

[#1005] A current carrying conductor is associated with
Correct Answer

(C) An electro-magnetic field

Explanation

Solution: A current carrying conductor, such as a metal wire, will produce a magnetic field around it because of the motion of charge within the wire itself. This motion produces or sets up a magnetic field around the wire in the form of concentric circles. This electromagnetic effect is described in physics by the Biot-Savart Law, an experimentally deduced inverse-square law. The effect is also described by Ampere’s Law, which is derived from the Biot-Savart Law.