Kuiz Fizik Tingkatan 5 Bab 4

SELAMAT DATANG Kuiz Fizik Tingkatan 5 Bab 4

KUIZ INI MENGANDUNGI 10 SOALAN

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

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

To increase the strength of the magnetic field.

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

To reduce energy loss due to friction.

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?

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.

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

None

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

Using a coil with more turns (lilitan).

Decreasing the current supplied to the coil.

Replacing the soft iron core with an air core.

Using weaker permanent magnets.

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?

Lenz’s Law

Fleming’s Right-Hand Rule

Fleming’s Left-Hand Rule

Right-Hand Grip Rule

None

What is the primary purpose of the soft iron core in a transformer?

To concentrate and guide the magnetic flux from the primary to the secondary coil.

To provide electrical insulation between the primary and secondary coils.

To step down the current while stepping up the voltage.

To prevent the transformer from overheating during operation.

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

12.5 turns

800 turns

None

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

Using a laminated soft iron core.

Using a soft iron core instead of a steel core.

Using thicker copper wires for the coils.

Winding the secondary coil on top of the primary coil.

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 total magnetic flux contained within the coil.

The strength of the current flowing in the conductor.

The rate of change of magnetic flux through the conductor.

The electrical resistance of the conductor.

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 power supply provides a brief surge of current.

The coil’s rotational inertia.

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

The magnetic field from the permanent magnets reverses.

None

10.

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

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

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

DC current is unable to magnetize the soft iron core.

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

None

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