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.