Magnetic Effect of Current

The direction of magnetic field around a straight conductor carrying current can be determined by

• Fleming’s left hand rule

• Lenz’s law

• Right hand thumb rule

• Fleming’s right hand rule

Answer explanation

The direction of the magnetic field around a straight conductor carrying current is determined by the Right Hand Thumb Rule. Point your thumb in the direction of the current, and your fingers curl in the direction of the magnetic field.

A magnetic Field exerts no force on

• a stationary electric charge

• a magnet

• an electric charge moving perpendicular to its direction

• an unmagnetised iron bar

Answer explanation

A magnetic field exerts no force on a stationary electric charge because the force on a charge is given by the equation F = q(v x B), where v is the velocity. If the charge is stationary, v = 0, thus F = 0.

At the centre of magnet, the magnetism is

• Zero

• same as at the poles

• maximum

• minimum

Answer explanation

At the center of a magnet, the magnetic field lines are parallel and evenly distributed, resulting in zero magnetism. This is in contrast to the poles, where the magnetic field is strongest.

Magnetic Field is

• Scalar quantity

• Vector quantity

• both (a) and (b)

• None of these

Answer explanation

Magnetic field is a vector quantity because it has both magnitude and direction. It is represented by arrows indicating the direction of the magnetic force, distinguishing it from scalar quantities that only have magnitude.

tesla is the unit of

• magnetic field

• electric field

• electric potential

• electric current

Answer explanation

Tesla is the unit of magnetic field strength, named after Nikola Tesla. It measures the strength of magnetic fields, distinguishing it from units for electric fields, potential, or current.

1 tesla is equal to

• 10 7 gauss

• 10 -4 gauss

• 10 4 gauss

• 10 -8 gauss

Answer explanation

1 tesla is equivalent to 10^4 gauss. This conversion is based on the relationship between the two units of magnetic flux density, where 1 tesla equals 10,000 gauss.

Gauss is the unit of

• magnetic field

• electric field

• electric potential

• electric current

Answer explanation

Gauss is the unit of magnetic field strength in the CGS (centimeter-gram-second) system. It measures the intensity of magnetic fields, making 'magnetic field' the correct answer.

A conductor carrying current from south to north deflects the magnetic needle placed parallel and above it towards

• East

• west

• north

• south

Answer explanation

According to the right-hand rule, if the current flows from south to north, the magnetic field lines will circle the conductor. This causes the magnetic needle to deflect towards the east.

The magnetic Field at a point due to current carrying conductor is directly proportional to the

• Current flowing through the conductor

• Distance from the conductor

• Voltage across the conductor

• Resistance of the conductor

Answer explanation

The magnetic field produced by a current-carrying conductor is directly proportional to the current flowing through it, as described by Ampère's law. Thus, the correct answer is 'Current flowing through the conductor'.

The magnetic field lines around a magnet are

• Closed loops

• Open loops

• Random

• Straight lines

Answer explanation

The magnetic field lines around a magnet are closed loops, originating from the north pole and returning to the south pole. This characteristic illustrates the continuous nature of magnetic fields.