PHYSICS TEST 3

I It retains its magnetic much longer than steel.
II It is more easily magnetized than steel
III It is more easily demagnetized than steel
IV It produces a stronger magnet than steel
Which combination of the above makes iron preferable to steel in the making of electromagnets?

• I and II only

• II and III only

• I, III, and IV only

• • II, III and IV only

  
  

In the diagram above, if the south-poles of two magnets strokes steel bar, the polarities at T and V will respectively be

• south and north

• north and south

• north and north

• south and south

The name given to the characteristics behavior of substances which set their length perpendicular to a strong magnetic field instead of in line with it is

• magnetization

• paramagnetism

• diamagnetism

• demagnetization

A bar magnet is placed near and lying along the axis of a solenoid connected to a galvanometer. The pointer of the galvanometer shows no deflection when?

• the magnet is moved towards the stationary solenoid

• there is no relative motion

• the magnet is moved away from the stationary solenoid

• the solenoid is moved away from the stationary magnet

The magnetic flux in a coil having 200 turns changes at the time rate of 0.08Ws^-1. The induced e.m.f in the coil is?

• 1.6 V

• 16.0 V

• 25.0 V

• 250.0 V

A proton moving with a speed of 1.0 × 10⁶ ms^-1 through a magnetic field of 1.0 T experiences a magnetic force of magnitude 8.0 × 10^-14 N. The angle between the proton's velocity and the field is?

• 45°

• 30°

• 60°

• 90°

A particle carrying a charge 1.0 × 10^-8 C enters a magnetic field at 3.0 × 10² ms^-1 at right angles to the field. If the force on this particle is 1.8 × 10^-8 N, What is the magnitude of the field?

• 6.0 × 10^-1 T

• 6.0 × 10^-2 T

• 6.0 × 10^-3 T

• 6.0 × 10^-4 T

A magnet is moved through a coil ofwire. The e.m.f produced in the wire depends on?

• The number of turns in the coil

• The strength of the magnet

• The speed at which the magnet is moved

• All of the above

• None of the above

Which of the following statements is NOT correct?

• A galvanometer can be converted to an ammeter with a different range by connecting a high resistance shunt in series

• An electric current always produces a magnetic field

• Maxwell's screw rule states that if a corkscrew moves in the direction of the current, the hand turns in the direction of the lines of force

• Electromagnets are used in electric bells and telephone receivers

• The lines of force round a straight current carrying conductor are circular

When two parallel wires carry currents in opposite directions, the force on either wire is

• Away from the other wire

• Zero, because the currents cancel each other

• Twice as much as when the currents are in the same direction

• Towards the other wire