Solutions of Magnetic Effects of Electric Current (Page No- 85 & 91) - Physics By Lakhmir Singh | Extra Documents, Videos & Tests for Class 10 PDF Download

Lakhmir Singh Physics Class 10 Solutions Page No:85

Question 1: What produces magnetism in the human body ?

Solution : Weak ionic currents flowing in the human body produce magnetism.

Question 2: Name one medical technique which is based on magnetism produced in human body. For what purpose is this technique used ?

Solution : The technique called Magnetic Resonance Imaging (MRI) is based on magnetism produced in human body. It is used for obtaining images of internal parts of the body.

Question 3: Name two human body organs where magnetism produced is significant.

Solution : Brain and heart.

Question 4: What is the full form of MRI ?

Solution : Magnetic Resonance Imaging.

Question 5: Name the technique by which doctors can produce pictures showing insides of the human body.

Solution : Magnetic Resonance Imaging (MRI)

Question 6: Name one technique which can detect cancerous tissue inside the body of a person. 

Solution : Magnetic Resonance Imaging (MRI).

Lakhmir Singh Physics Class 10 Solutions Page No:91

Question 1: What happens when a current-carrying conductor is placed in a magnetic field ?

Solution : When a current-carrying conductor is placed in a magnetic field, a mechanical force is exerted on the conductor which can make the conductor move.

Question 2: When is the force experienced by a current-carrying conductor placed in a magnetic field largest ?

Solution : The force experienced by a current-carrying conductor placed in a magnetic field is the largest when the current carrying conductor is at right angles to the magnetic field.

Question 3: In a statement of Fleming’s left-hand rule, what do the following represent ?
 (a) direction of centre finger.
 (b) direction of forefinger.
 (c) direction of thumb.

Solution : (a) Current.
(b) Magnetic field.
(c) Force acting on the conductor.

Question 4: Name one device which works on the magnetic effect of current.

Solution : Electric bell works on the magnetic effect of current. It uses an electromagnet to produce sound.

Question 5: Name the device which converts electrical energy into mechanical energy.

Solution : Electrical motor.

Question 6: A motor converts one form of energy into another. Name the two forms.

Solution : Electrical energy to mechanical energy.

Question 7: State whether the following statement is true or false :
 An electric motor converts mechanical energy into electrical energy.

Solution : False
An electric motor converts electrical energy into mechanical energy.

Question 8: For Fleming’s left-hand rule, write down the three things that are 90° to each other, and next to each one write down the finger or thumb that represents it.

Solution : (a) Current – direction of center finger.
(b) Magnetic field – direction of fore finger.
(c) Force or Motion – direction of thumb.

Question 9: Name the device which is used to reverse the direction of current in the coil of a motor.

Solution : A commutator reverses the direction of current in the coil of a motor.

Question 10: What is the other name of the split ring used in an electric motor ?

Solution : Commutator.

Question 11: What is the function of a commutator in an electric motor ?

Solution : The function of commutator rings is to reverse the direction of current flowing through the coil every time the coil just passes the vertical position during a revolution.

Question 12: Of what substance are the brushes of an electric motor made ?

Solution : Carbon.

Question 13: Of what substance is the core of the coil of an electric motor made ?

Solution : The core of the coil of an electric motor made of soft iron.

Question 14: In an electric motor, which of the following remains fixed and which rotates with the coil ?
 Commutator ; Brush

Solution : Brush remains fixed. Commutator rotates with the coil.

Question 15: What is the role of the split ring in an electric motor ?

Solution : The function of split rings is to reverse the direction of current flowing through the coil every time the coil just passes the vertical position during a revolution.

Question 16: Fill in the following blanks with suitable words :
 (a) Fleming’s Rule for the motor effect uses the…………………..
 (b) A motor contains a kind of switch called a……………………. which reverses the current every half…………………..

Solution : (a) left
(b) Commutator; rotation.

Question 17: (a) A current-carrying conductor is placed perpendicularly in a magnetic field. Name the rule which can be
 used to find the direction of force acting on the conductor.
 (b) State two ways to increase the force on a current-carrying conductor in a magnetic field.
 (c) Name one device whose working depends on the force exerted on a current-carrying coil placed in a magnetic field.

Solution : (a) Fleming’s left hand rule.
(b) By increasing the current flowing in the conductor; by increasing the strength of magnetic field.
(c) Electric motor.