Physics Electromagnetism Quiz

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Questions and Answers

What does the thumb represent when determining the direction of force on a current-carrying wire in a magnetic field?

Direction of motion of the wire (correct)

Direction of the magnetic flux density

Direction of current through the wire

Direction of the magnetic field

What is the role of the carbon brushes in a slip ring system?

To rotate with the coil

To change the direction of current flow

To provide contact with the external circuit (correct)

To induce electric current in the coil

Which of the following factors does NOT affect the force acting on a current-carrying wire in a magnetic field?

Length of the wire

Temperature of the wire (correct)

Magnetic flux density

Current in the wire

How many brushes are in contact with the slip rings in this system?

Two graphite brushes Signup and view all the answers

Which statement is true about the brushes in this system?

They do not rotate with the coil Signup and view all the answers

What effect does cutting the primary coil have on the secondary coil?

It induces an emf in the secondary coil. Signup and view all the answers

If the magnetic flux density (B) is doubled while keeping the current (I) and length (L) constant, what happens to the force (F) on the wire?

Doubles Signup and view all the answers

What happens to the galvanometer pointer if the primary switch has been closed for a few seconds?

The pointer remains at zero. Signup and view all the answers

How is the force (F) on a current-carrying wire mathematically represented?

F = Constant × I × B × L Signup and view all the answers

What units should magnetic flux density (B) be in to ensure that the force (F) is measured in Newtons?

Tesla (T) Signup and view all the answers

What happens to the induced currents in the coil?

They pass to the external circuit through the brushes Signup and view all the answers

What material are the brushes commonly made from in this setup?

Carbon Signup and view all the answers

Which statement accurately describes the relationship between emf and galvanometer movement?

A sudden emf causes the galvanometer pointer to be deflected. Signup and view all the answers

If electric current through the primary coil is constant, what can be inferred about the secondary coil?

There will be no induced emf in the secondary coil. Signup and view all the answers

What is the primary consequence of cutting the primary coil without any current in it?

There is no induced emf in the secondary coil. Signup and view all the answers

What causes the induced current to flow in the coil?

The rotation of the coil across magnetic field lines Signup and view all the answers

Which rule determines the direction of the induced current in the coil?

Fleming’s right-hand rule Signup and view all the answers

What characteristic of the induced current is affected by the motion of the coil?

The intensity of the current Signup and view all the answers

What happens to the magnetic flux linked with the coil when it rotates?

It changes Signup and view all the answers

Which of the following best describes the nature of the induced current when the coil rotates?

It has variable intensity and changing direction Signup and view all the answers

What happens to the direction of the induced current in the external circuit as the coil rotates?

It alternates every half a rotation. Signup and view all the answers

What type of current is induced in the external circuit due to the rotation of the coil?

Alternating current Signup and view all the answers

How frequently does the induced current change direction as the coil completes a rotation?

Every half a rotation. Signup and view all the answers

Why does the induced current not remain constant?

As a result of the rotation of the coil. Signup and view all the answers

What aspect of the coil's movement leads to the alternating current?

Its continuous rotation. Signup and view all the answers

Study Notes

Fleming's Left-Hand Rule

Thumb points in the direction of motion of the wire.
Pointer (first finger) points in the direction of the magnetic field.
Middle (second finger) points in the direction of the current through the wire.

Factors Affecting Force on a Current-Carrying Wire

Force is proportional to the length of the wire (FαL)
Force is proportional to the current in the wire (FαI)
Force is proportional to the magnetic flux density (FαB)
Therefore, Force (F) is proportional to IBL: F = Constant ×I B L

Induced EMF in Secondary Coil

When a switch in the primary coil is closed, an induced EMF is generated in the secondary coil.
The induced EMF causes the galvanometer pointer to deflect.
If the switch in the primary coil is closed for an extended period, there is no induced EMF in the secondary coil.

Slip Rings and Carbon Brushes

Each slip ring is connected to a carbon brush that remains stationary.
The induced currents in the coil pass through the slip rings and carbon brushes to the external circuit.

Alternating Current Generation

When the coil rotates, its sides cut across magnetic field lines, causing a change in magnetic flux linked with the coil.
This change in flux induces a current in the coil.
The induced current has a variable intensity and changing direction, determined by Fleming’s right-hand rule.
The induced current in the external circuit changes direction every half rotation of the coil, resulting in an alternating current.

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Description

Test your knowledge on Fleming's Left-Hand Rule and the factors affecting the force on a current-carrying wire. This quiz also covers induced EMF in secondary coils and the role of slip rings and carbon brushes in electromagnetism. Prepare to challenge yourself with these key concepts!