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?

Using a coil with more turns (lilitan).

Using weaker permanent magnets.

Replacing the soft iron core with an air core.

Decreasing the current supplied to the coil.

None

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

To increase the strength of the magnetic field.

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

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

To reduce energy loss due to friction.

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?

South pole

The polarity will alternate rapidly.

It will have no magnetic polarity.

North pole

None

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

Using thicker copper wires for the coils.

Using a soft iron core instead of a steel core.

Winding the secondary coil on top of the primary coil.

Using a laminated soft iron core.

None

What is the key structural difference in the way the coil connects to the external circuit in an AC generator versus a DC generator?

An AC generator uses slip rings, while a DC generator uses a split-ring commutator.

An AC generator has more coil turns than a DC generator.

A DC generator uses permanent magnets, while an AC generator must use electromagnets.

The coil rotates clockwise for AC output and counter-clockwise for DC output.

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 rotational force on the coil sides is at its maximum.

The power supply provides a brief surge of current.

The coil’s rotational inertia.

The magnetic field from the permanent magnets reverses.

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

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 electrical resistance of the conductor.

The rate of change of magnetic flux through the conductor.

The strength of the current flowing in the conductor.

The total magnetic flux contained within the coil.

None

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

To provide electrical insulation between the primary and secondary coils.

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

To step down the current while stepping up the voltage.

To prevent the transformer from overheating during operation.

None

10.

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

DC current is unable to magnetize the soft iron core.

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.

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

None

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