Cls 10 Sci Chp 13 prevs yr qn ans

 Class 10 Science 

 Previous Years Appeared Questions and Answer 

 Chapter 13 Magnetic Effects of Electric Current 

Multiple Choice Questions 

1. The device used to produce electricity is  (April - 2022)

(A) Galvanometer 

(B) Electric generator

(C) Electric generator 

(D) Electric motor.

Ans: (B) Electric generator

2. In Fleming’s right hand rule, the middle finger indicates the direction of  (April - 2022)

(A) induced electric current

(B) magnetic field

(C) motion of the conductor

(D) mechanical force.

 Ans. : (A) induced electric current

3. Observe the diagram.

The magnetic poles represented by P and Q respectively are  (Sep - 2020)

(A) south ( ) and south (S)

(B) north ( N ) and south ( S )

(C) north (N) and north (N)

(D) south (S) and north (N)

Ans. :  (A) south (S) and south (S) 

4. A device that converts electrical energy into mechanical energy is (June 2023) 

(A) Electric generator   (B) Electric motor 

(C) Galvanometer        (D) Voltmeter. 

Ans. : (B) Electric motor

5. Imagine, you are holding a straight current carrying conductor as per the right hand thumb rule. If the thumb is upward, then the direction of the field lines of the magnetic field is (June 2023)

(A) downward          (B) upward

(C) anti-clockwise  (D) clockwise.

Ans. :

(C) anti-clockwise

6. In Fleming’s left hand rule the middle finger represents the direction of (Aug 2024)

(A) magnetic fieldb                  (B) current 

(C) movement of conductor  (D) induced current 

Ans. : (B) current 

7. The magnetic field inside a long straight solenoid carrying current (June 2024)

(A) is the same at all points 

(B) is zero 

(C) decreases as we move towards its end 

(D) increases as we move towards its end 

Ans. : (A) is the same at all points

One Mark Questions 

1. What are the reasons for occurring overload in an electric circuit ? (June - 2022)

Ans:

★  Accidental hike in the supply voltage.

★  Connecting too many appliances to a single socket.

★  When live wire and neutral wire come into direct contact.               ( Any two )

2. Magnetic field lines do not intersect each other. Why ? (April - 2022)

Ans. :

At the point of intersection the compass needle would point towards two directions which is not possible.

3. Suggest any two measures to avoid overloading in domestic circuits. (Sep - 2020)

Ans. :

★ Live and neutral wires should not come into direct contact.

                 OR

★ There should not be any short-circuit in the circuit.

★ Too many appliances should not be connected to a single socket.

★ Should always use quality wires and good quality electrical appliances.                                                     (Any Two)

4. Observe the given figure. 

What type of current is induced in the coil by doing the experiment related to this figure ? Give reason for your answer. (June - 2020)

Ans. :  

★ Alternating current

★ Because the deflections in the galvanometer would just be opposite to the previous. 

( Or galvanometer deflections are in opposite directions )

5. Observe the figure and mention the direction of the force acting on the current carrying conductor AB. Name the rule that helped you to find the direction of the force. (June 2023)

Ans. :

★ Towards left

OR

Towards the magnet ( Or towards north pole of

the magnet )

★ Fleming’s left hand rule

6. What does the thumb indicate in the right hand thumb rule? (April 2023)

Ans. :

Direction of current

Two Marks Questions 

1. Draw the diagram of a simple electric motor and label ‘Split rings’ ? (June - 2022) (June - 2020)

Ans:

2. Explain how overloading occurs in domestic electric circuit ? (June - 2020)

Ans. :

★ Over loading can occur when the live wire and the neutral wire come into direct contact

★ It can also occur due to an accidental hike in the supply voltage.

★ Sometimes overloading is caused by connecting too many appliances to a single socket.         (Any two)

3. In domestic wiring electrical appliances are not connected in series. Why ? (June - 2020)

Ans. :

★In series arrangement if one appliance fails to work, then the circuit is broken and remaining appliances do not work.

★ The appliances in series draw same current in the circuit and hence do not operate properly. 

4. Observe the given figures and answer the questions that follow :

i) Which of the above figures shows the correct direction of magnetic field ? 

ii) Name and state the rule that helped to choose the correct figure. (Aug 2024)

Ans. : 

 i) Figure (b) shows the correct direction of magnetic field.

 

ii) Right hand thumb rule helps to choose the correct figure. 

Statement : Holding a current carrying straight conductor in right hand such that the thumb indicates the direction of current and the fingers wrapping around the conductor indicates direction of field lines of the magnetic field. 
 

Three Marks Questions 

1. List the properties of the magnetic field due to the flow of electric current in a solenoid. What are the two methods of increasing magnetic field in a solenoid ? (June - 2022)

Ans. :

★ The magnetic field in a current carrying solenoid is similar to that of magnetic field produced in a bar magnet.

★  The magnetic field is uniform inside the solenoid.

The two methods to increase magnetic field in a solenoid. 

¡) By increasing the number of turns of the coil.

¡¡) By increasing the current flowing through solenoid.

2. What are the functions of an earth wire ? It is necessary to connect the electric appliances having metallic body to earth wire in domestic electric circuit. Why ? Explain. (April - 2022)

Ans. :

Functions of the earth wire :

★ This is used as a safety measure for appliances have metallic body in domestic circuit

★This provides a low resistance conducting path for the current

★Any leakage of current in the appliances keeps its potential to that of the earth and the user may not get a severe electric shock.

3. Explain Faraday’s experiment related to electromagnetic induction. Mention the difference between direct and alternate current. (April - 2022)

Ans:

★ Take a coil of copper wire having a large number of turns connect the ends of the coil to a galvanometer 

★ Take a strong magnet and move its one pole into the coil 

★ There is a deflection in the needle of the galvanometer. This indicates the presence of a current in the coil 

★Likewise, when the magnet is withdrawn back then also the needle of galvanometer deflects and this indicates the presence of electric current.

4. Observe the given diagram :

Explain the experiment related to this diagram. What conclusions can be drawn from this experiment? (June 2023)

Ans. :

★ Take two different coils of copper wire say 100 and 50 turns respectively. Insert them over a non-conducting cylindrical roll.

★ Connect the Coil-1 in series with a battery and plug key, Coil-2 with galvanometer

★ When the key is plugged in, needle of the galvanometer deflects and returns to zero. This indicates the presence of current in the Coil-2

★ Disconnect Coil-1 from battery. Needle of the

galvanometer deflects in the opposite direction and returns to zero. This indicates the opposite direction of the current.

Conclusions :

★ Changing electric current in Coil-1 induces current in Coil-2. This is electromagnetic induction.

★ This is due to the change in the magnetic field.

5. In domestic circuits, 

i) What are the reasons for overloading ? 

ii) Explain the working of earth wire. (April 2024)

Ans. :  i) Reasons for overload : 

★ When the live wire and neutral wire come into direct contact. 

★ Leakage of current in electrical appliances 

★ Connecting too many appliances to the single socket. 

ii) Working of earth wire :  

★ The metallic body of electrical appliances are connected to the earth wire. If any leakage of current occurs in the electrical appliances, keep their potential difference same as to that of the earth and user may not get severe electric shock.

6. A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is 

i) pushed into the coil ? 

ii) withdrawn from inside the coil ? iii) held stationary inside the coil ? (April 2024)

Ans:

★  The needle of the galvanometer deflects. 

★  The needle of the galvanometer deflects in the direction opposite to the first 

★  The needle of the galvanometer does not deflect needle indicates zero.

 

Four Marks Questions 

1. Observe the given diagram. Explain the experiment related to this diagram. What conclusions can be drawn from this experiment ? (Sep - 2020)

Ans:

★ The ends of the copper coil ( AB ) are connected to a galvanometer. The north pole of the bar magnet ( NS ) is moved inside the coil. Induced current is produced in the coil and hence the needle of the galvanometer shows momentary deflection in one direction.

★ When the north pole of the magnet is withdrawn from the coil, the needle of the galvanometer is deflected in the opposite direction.

★ When the magnet is held stationary inside the coil, the deflection of the galvanometer drops to zero ( shows no deflection ).

★ When the magnet is moved inside the coil with greater force, galvanometer shows greater deflection and when the magnet is moved with smaller force, the galvanometer shows smaller deflection. When the magnet is stationary and the coil is moved towards / away from the magnet, galvanometer show deflection.

Conclusions that can be drawn from this experiment :

★ Motion of the magnet with respect to the coil produces an induced potential difference, which sets up an induced electric current in the circuit. 

                    OR

★ The direction of the induced current depends on the direction of the movement of the magnet inside the coil.

★ The amount of induced current is directly proportional to the force with which the magnet is moved into or withdrawn from the coil. 

2. How do you trace the magnetic field lines around a bar magnet using compass needle ? Explain. Write the properties of magnetic field lines. (June - 2020)

Ans. :

★ Take a small compass and a bar magnet. Place a magnet on a sheet of white paper fixed on a drawing board. Mark the boundary of the magnet.

★ Place the compass near the north pole of the magnet mark the position of two ends of the needle.

★ Now move the needle to a new position such that the south pole occupies the position previously occupied by its north pole.

★ In this way proceed step by step till we reach the south pole of the magnet. Join the points marked on the paper by a smooth curve. This represents field line.

★ Repeating above procedure we can draw as many lines as possible.

Properties of magnetic field lines :

★ Field lines emerge from north pole and merge at the south pole.

★ At the poles field lines are crowded.

★ No two field lines are found to cross each other.  

3. a) What is solenoid? Write the properties of the magnetic field lines formed around a current carrying solenoid.

b) What is alternating current? Electric appliances having metallic body are connected to earth wire, why? (June 2023)

Ans. :

a)

★ A coil of many circular turns of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid.

★ At the ends/poles of a solenoid, the magnetic fieldnlines appear in the form of concentric circles.

★ At the centre / inside the solenoid the magnetic field lines appear in the form of parallel straight lines.

b)

★The current that changes direction after equal intervals of time is called an alternating current.

★ The metallic body is connected to the earth wire provides a low resistance conducting path for the current.

★ Thus, it ensures that any leakage of current to the metallic body of the appliance keeps its potential to that of the earth and the user may not get a severe electric shock.

4. a) State the right hand thumb rule. Write any two properties of the magnetic field lines. 

b) What is solenoid ? How can this be converted into an electromagnet ? (April 2024)

Ans. : Right hand thumb rule : 

a) When you are holding a current carrying conductor such that the thumb points towards the direction of current then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field. 

Properties of the magnetic field lines : 

★ emerge from north pole and merge at the south pole. 

★ closed curves 

★ never intersect each other 

★ have magnitude and direction. 

b) Solenoid : A coil of many circular turns of insulated copper wire wrapped closely in the shape of cylinder is called a solenoid. 

Current carrying solenoid can be used to magnetise a piece of magnetic material like soft iron when placed inside the coil. 

5. a) Explain an experiment of drawing magnetic field lines around a bar magnet with the help of a compass needle. 

b) Mention two properties of magnetic field lines. (June 2024)

Ans. : a) Drawing magnetic field lines around a bar magnet using a compass needle : 

★ Place a bar magnet on a white paper and mark the boundary of the magnet 

★ Place the compass needle near the north pole of the magnet. The south pole of the compass needle directs towards the north pole of the magnet. Mark it with a point. 

★ Move the needle to a new position such that its south pole occupies the position previously occupied by its north pole. Mark it with a point. 

★ In this way proceed step by step till you reach the south pole of the magnet. 

★ Join the points marked on the paper by a small curve. 

★ This curve represents a field line

b) Properties of magnetic field lines : 

★ Field lines emerge from north pole of a magnet and merge at south pole. 

★ Inside the magnet the direction of the field lines is from its south pole to north pole. 

★ Magnetic field lines are closed curves.

★ Magnetic field is stronger where the field lines are crowded. 

★ No two field-lines are found to cross each other. ( Any two )   

6. a) Explain an experiment to show that a current carrying conductor experiences the force in a magnetic field. 

b) How is a simple electric motor converted into a commercial motor ? (June 2024)

Ans: 

a) 

★  Take a small aluminium rod and suspend it horizontally using connecting wires.

★  Place a strong horse-shoe magnet in such a way that rod lies between the two poles with the magnetic field directed upwards. 

★  Connect the aluminium rod in series with a battery, a key and a rheostat. 

★  Now pass the current through the aluminium rod in one particular direction. 

★  The rod displaces towards one side. 

★  Reverse the direction of current flowing through the rod. The rod displaces towards the opposite side.  

Hence a current carrying conductor experiences a force perpendicular to its length in a magnetic field. 

 b) 

★ By replacing permanent magnet with an electromagnet. 

★  By increasing the number of turns of the conducting wire in the current-carrying coil. 

★  By using a soft iron core on which the coil is wounded. ( Any two )