Kuiz Fizik Tingkatan 5 Bab 4

SELAMAT DATANG Kuiz Fizik Tingkatan 5 Bab 4

KUIZ INI MENGANDUNGI 10 SOALAN

Which of the following changes would increase the rate of rotation of a DC electric motor?

Replacing the soft iron core with an air core.

Using a coil with more turns (lilitan).

Decreasing the current supplied to the coil.

Using weaker permanent magnets.

None

According to Faraday's Law of Induction, the magnitude of the induced electromotive force (e.m.f.) in a conductor is directly proportional to what?

The rate of change of magnetic flux through the conductor.

The electrical resistance of the conductor.

The total magnetic flux contained within the coil.

The strength of the current flowing in the conductor.

None

An ideal step-up transformer is designed to change a 12 V input to a 48 V output. If the primary coil has 50 turns, how many turns must the secondary coil have?

200 turns

50 turns

800 turns

12.5 turns

None

What is the primary function of the split-ring commutator in a direct current (DC) motor?

To reverse the direction of the current in the coil every half rotation.

To reduce energy loss due to friction.

To increase the strength of the magnetic field.

To connect the motor to an alternating current (AC) supply.

None

Which of the following rules is used to determine the direction of the force experienced by a straight wire carrying a current within a magnetic field?

Fleming’s Left-Hand Rule

Lenz’s Law

Fleming’s Right-Hand Rule

Right-Hand Grip Rule

None

In a simple DC motor, the coil continues to rotate past the vertical position even though the current is momentarily cut off. What is the reason for this continued rotation?

The magnetic field from the permanent magnets reverses.

The rotational force on the coil sides is at its maximum.

The power supply provides a brief surge of current.

The coil’s rotational inertia.

None

The force on a current-carrying wire in a magnetic field results from a 'catapult field'. In which region of this resultant field is the magnetic field weakest?

Where the field lines from the wire and the permanent magnet are in opposite directions.

Along the central axis of the permanent magnet’s field.

Directly above the wire, regardless of field direction

Where the field lines from the wire and the permanent magnet are in the same direction.

None

Which modification would most effectively increase a transformer's efficiency by reducing energy loss from eddy currents?

Using a soft iron core instead of a steel core.

Winding the secondary coil on top of the primary coil.

Using thicker copper wires for the coils.

Using a laminated soft iron core.

None

When the north pole of a bar magnet is pushed towards a solenoid, a current is induced. According to Lenz's Law, what will be the magnetic polarity of the end of the solenoid closest to the approaching magnet?

The polarity will alternate rapidly.

South pole

It will have no magnetic polarity.

North pole

None

10.

Why will a transformer not operate if its primary coil is connected to a direct current (DC) power supply?

The resistance of the primary coil is too high for DC to flow.

A DC supply produces a constant magnetic field, which does not induce a current in the secondary coil.

The secondary coil is designed in a way that only allows alternating current to be generated.

DC current is unable to magnetize the soft iron core.

None

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