# CBSE Class 10th Science 13 – Magnetic effects of electric current MCQs

#### Current carrying conductor placed in a magnetic field experiences a force. The device based on the principle is ____.

Correct! Wrong!

An electric motor consists of coil placed in a magnetic field. When current flows through it, it experiences torque. Hence, electric motor is the device which works on the principle based on the force experienced by the current carrying conductor placed in a magnetic field.

#### A rectangular coil of copper wire is rotated in a magnetic field. The direction of the induced current changes once for ____revolution of the coil.

Correct! Wrong!

The direction of the induced current changes once for half revolution of the coil.

#### The direction of induced current in a circuit is given by ____.

Correct! Wrong!

The direction of induced current in a circuit is given by Fleming’s right-hand rule.

#### The essential difference between an AC generator and a DC generator is:

Correct! Wrong!

AC generator has slip rings while the DC generator has a commutator.

#### The magnetic lines of force due to a straight conductor carrying current are ____.

Correct! Wrong!

The magnetic lines of force due to a straight conductor carrying current are concentric circles with conductor passing through centre and perpendicular to their plane.

#### Electromagnetic induction is involved in the development of current ____.

Correct! Wrong!

Electromagnetic induction is involved in development of current by relative motion between the magnetic field and the coil.

#### An electrical generator or dynamo is a device which converts electrical energy into mechanical energy.

Correct! Wrong!

An electrical generator or dynamo is a device which converts mechanical energy into electrical energy.

#### An alternating electric current with a frequency of 50 Hz, will change its direction ____ times per second.

Correct! Wrong!

An alternating electric current with a frequency of 50 Hz, will change its direction 100 times per second.

#### Which of the following part differentiates an AC generator from DC generator?

Correct! Wrong!

Slip rings are the essential part of an AC generator. Hence, slip rings differentiates an AC generator from DC generator.

#### Direct current flows with varying magnitude in the opposite direction.

Correct! Wrong!

Direct current flows with constant or varying magnitude in the same direction.

#### A current whose magnitude changes continuously with time and whose direction reverses, at regular intervals of tiA current whose magnitude changes continuously with time and whose direction reverses, at regular intervals of time is called direct current.me is called direct current.

Correct! Wrong!

An alternating current is that current, whose magnitude changes continuously with time and whose direction reverses at regular intervals of time.

#### Which of the following is a source of alternating current?

Correct! Wrong!

Thermal power plants cannot be considered as a source of direct current. They generate alternating current, while dry cells, button cells and lead accumulators are sources of direct current.

#### When the direction of current in a conductor is reversed, then the deflection of the needle of the compass placed near a current carrying conductor ____.

Correct! Wrong!

When the direction of the current in a conductor is reversed, then the direction of the deflection of the compass needle placed near a current carrying conductor reverses. The change in the direction of current reverses the direction of the needle but the angle of deflection is the same.

#### Which of the following property of a proton can change, when it moves in a magnetic field?

Correct! Wrong!

When a proton moves in a magnetic field, it experiences force. Due to this force the velocity of the proton changes but its mass, charge and size does not change.

#### At the time of a short circuit, the current in the circuit ____.

Correct! Wrong!

Short circuit occurs when a live wire comes in connect with another live wire or neutral wire. During short circuit resistance of the circuit is almost zero. Hence, the current increases heavily in the circuit at the time of a short circuit.

#### The speed of rotation of an electric motor can be increased by ____.

Correct! Wrong!

The speed of rotation of an electric motor is increased by increasing the strength of the magnetic field.

#### A charged body at rest produces ____.

Correct! Wrong!

A charged body at rest produces only electric field.

#### A charge at rest gets deflected by magnetic field.

Correct! Wrong!

A charge at rest does not produce magnetic fields around it. So, a charge at rest cannot be deflected by magnetic fields.

#### The frequency of AC mains used in India is ____.

Correct! Wrong!

Frequency used of AC mains used in India is 50 cps.

#### Which part of an AC generator ensures that current produced in the external circuit is alternating?

Correct! Wrong!

A slip rings arrangement in an AC generator ensures that current produced in the external circuit is alternating.

#### The force on a charged particle moving in a magnetic field is maximum, when the angle between the direction of motion and field is ____.

Correct! Wrong!

The force on a charged particle moving in a magnetic field is maximum, when the angle between direction of motion and field is 90°.

#### A positive charge projected towards east is deflected towards north by a magnetic field. The magnetic field is directed ____.

Correct! Wrong!

The direction of magnetic field will be downward if a positive charge projected towards east is deflected towards north by a magnetic field.

#### The strength of magnetic field produced by a current carrying solenoid does not depend upon the ____.

Correct! Wrong!

The strength of magnetic field produced by a current carrying solenoid does not depend upon the direction of current. The strength of the magnetic field produced by a solenoid depends on: 1. Number of turns per unit length of the solenoid 2. Strength of the current in the solenoid 3. nature of the core present inside the solenoid

#### An electric short circuit does not occur when the ____.

Correct! Wrong!

An electric short circuit does not occur when the neutral wire touches the earth wire. Short circuits are most likely to occur: 1. When two live wires touch each other. 2. When a live wire and a neutral wire come in contact. 3. When a live wire and an earth wire come in contact.

#### An alternating current is that current, which changes its direction regularly but not the magnitude.

Correct! Wrong!

An alternating current is that current, which changes its direction and magnitude regularly.

#### An electric transmitting wire is stretched in the direction of north to south. The current in wire flows from south to north. The direction of magnetic field due to the wire at a point above the conductor is ____.

Correct! Wrong!

According to right hand rule, the direction of magnetic field due to the wire at a point above the conductor is towards east.

#### Magnetic field does not interact with ____.

Correct! Wrong!

Magnetic fields do not interact with electric charges at rest, because charges at rest does not produce magnetic fields around them. Only moving charge experiences force in a magnetic field.

#### The phenomenon of electromagnetic induction is ____.

Correct! Wrong!

Electromagnetic induction is the process of inducing current in a coil due to relative motion between a magnet and the coil.

#### The scientist who first established the relation between electricity and magnetism is ____.

Correct! Wrong!

H.C. Oersted first established the relation between electricity and magnetism.

#### An alpha particle projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is ____.

Correct! Wrong!

According to Fleming’s left hand rule, when thumb, forefinger and middle finger are stretched mutually perpendicular to each other, then the motion of charge particle is represented by middle finger, the magnetic field direction is represented by forefinger and the thumb represents the direction of the force acting on it. Hence, the direction of magnetic field is vertically upwards.

CBSE Class 10th Science 13 - Magnetic effects of electric current MCQs
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