MAGNETIC EFFECTS OF CURRENT

What is that instrument which can detect the presence of electric current in a circuit?

• galvanometer

• motor

• generator

• none of above

The direction of magnetic field developed around a current -carrying conductor can be easily found by the use of

• right hand thumb rule

• left hand thumb rule

• Fleming's left hand rule

• Fleming's right hand rule

The strength of magnetic field around a current - carrying straight conductor

• is same every where around the conductor

• is directly proportional to the square of distance of a point from the conductor

• is directly proportional to the current flowing in the conductor

• is inversely proportional to the current

What should be the core of an electromagnet?

• soft iron

• hard iron

• rusted iron

• none of above

The strength of a magnetic field inside a long current-carrying straight solenoid coil is

• more at the ends than at the centre

• minimum in the middle

• same at all points

• found to increase from one end to the other

A magnetic field existing around a magnet can be represented by magnetic field lines. Magnetic field lines always form

• open loops

• closed loops

• straight lines

• both closed loops and straight lines

A vertical wire carries a current straight down. To the east of this wire , the magnetic field points:

• southwards

• downwards

• eastwards

• northwards

If a charged particle does not experience any force in a magnetic field, then..

• A) it is stationary

• B) it moves in the direction parallel to magnetic field

• both A and B

• it moves perpendicular to the field

The function of commutator or slip ring is to

• increase the current flowing through the coil

• change the direction of current through coil

• decrease the current flowing through the coil

• change the direction of magnetic field

A beam of alpha particles enters a chamber moving along the magnetic field. The force acting on them is

• maximum and perpendicular to the magnetic field

• maximum and along the magnetic field

• minimum and perpendicular to the magnetic field

• zero