Class 10 Science · Chapter 12

Magnetic Effects of Electric Current

279 Class 10 Science questions on Magnetic Effects of Electric Current from the NCERT textbook, NCERT Exemplar and CBSE board papers 2018–2026, each with its answer and a step-by-step solution.

NCERT exercises

Exercises (9) Intext Questions (Page 196) (1) Intext Questions (Page 200) (3) Intext Questions (Page 201) (3) Intext Questions (Page 203) (3) Intext Questions (Page 205) (3)

NCERT Exemplar exercises

Multiple Choice Questions (12) Short Answer Questions (12) Long Answer Questions (8)

CBSE Class 10 Science previous year papers, with answers →

Questions · page 9 of 14

Q161 CBSE 2024
(a) State
1. (i)right-hand thumb rule, and
2. (ii)Fleming’s left-hand rule. (b) Using Fleming’s left-hand rule determine the direction of force experienced by a proton, which enters vertically downwards in a uniform magnetic field acting horizontally from west to east as shown in the diagram.
Show answer

The force on the proton is perpendicular to the plane of the paper, outwards, towards the reader, that is towards the south.
(a) (i) Right-hand thumb rule: hold a current-carrying straight conductor in the right hand with the thumb pointing in the direction of the current; the fingers wrapped round the conductor then point in the direction of the magnetic field lines. (ii) Fleming's left-hand rule: stretch the thumb, forefinger and middle finger of the left hand so that they are mutually perpendicular; if the forefinger points in the direction of the magnetic field and the middle finger in the direction of the current, the thumb points in the direction of the force on the conductor. (b) A proton is positively charged, so the current is along its motion, vertically downwards. With the forefinger towards the east (the field) and the middle finger downwards (the current), the thumb points out of the plane of the paper. The force on the proton is therefore perpendicular to the plane of the paper, directed outwards, towards the reader, that is, towards the south.

Step-by-step solution →
Q162 CBSE 2024
1. (a)Draw the pattern of magnetic field lines around a current carrying straight conductor through which current is flowing vertically upward. Mark the direction of the field lines corresponding to the direction of current in the conductor.
2. (b)An alpha particle enters a uniform magnetic field at right angles to it as shown in the diagram. (i) Name the rule which can help in determining the direction of force acting on the alpha particle in this case. (ii) Apply this rule and find the direction of force on the alpha particle.
Show answer

Field lines are anticlockwise circles seen from above; Fleming's left-hand rule gives a force on the $α$ particle out of the page.
(a) The magnetic field lines are concentric circles centred on the conductor, lying in a horizontal plane at right angles to it and spaced more widely farther from the wire; for a current flowing vertically upward they run anticlockwise when seen from above (right-hand thumb rule). (b)(i) Fleming's left-hand rule. (ii) The $α$ particle is positively charged, so its downward motion is a current flowing downward. With the forefinger along the field (to the right) and the middle finger along the current (downward), the thumb points out of the page: the force on the $α$ particle acts perpendicular to the plane of the paper, towards the reader.

Step-by-step solution →
Q163 CBSE 2024
1. (i)Name two safety measures commonly used in electric circuits and appliances.
2. (ii)The power rating of an electric oven is 220 V; 2 kW. If it is used in a domestic electric circuit of current rating of 5A, what result do you expect ? Justify your answer with necessary calculations.
Show answer

Fuse and earthing; the oven draws about $9.1$ A against the 5 A rating, so the circuit is overloaded and the fuse melts.
(i) Electric fuse, and earthing (the earth wire connected to the metal body of appliances). (ii) Current drawn by the oven: $I = P / V = 2000 W /220 V \approx 9.1$ A. This is more than the 5 A rating of the circuit, so the circuit is overloaded: the fuse will melt and cut off the supply, and without a fuse the wiring would overheat and could catch fire. The oven should be used on a 15 A circuit.

Step-by-step solution →
Q164 CBSE 2024

List three advantages of parallel circuits in domestic wiring.

Show answer

Each appliance gets the full 220 V, works independently with its own switch, and draws the current it needs.
(i) Each appliance gets the same, full mains voltage (220 V), because every branch is connected directly across the live and neutral wires. (ii) Each appliance can be switched on or off independently with its own switch, and if one appliance is switched off or fails, the others continue to work. (iii) Each appliance draws the current it needs according to its own resistance (the current divides among the branches, and the total resistance is less than the smallest individual resistance), so gadgets needing very different currents, such as a bulb and a heater, work properly together.

Step-by-step solution →
Q165 CBSE 2024
1. (a)How is the type of current used in household supply different from the current given by a battery of dry cells ?
2. (b)Which one of the two currents mentioned above in (a) is considered to be more advantageous for the long distance transmission of electric power and why ? (c) How does the electric fuse prevent the electric circuit and the appliances from a possible damage due to short circuiting ?
Show answer

Household supply is AC (direction reverses) and a battery gives DC; AC suits long-distance transmission; a fuse melts to break the circuit.
(a) The household supply is alternating current (AC), which reverses its direction periodically; in India it changes direction every $\frac{1}{100}$ s (frequency $50$ Hz). A battery of dry cells gives direct current (DC), which flows in one direction only. (b) AC is more advantageous, because electric power can be transmitted over long distances as AC without much loss of energy: its voltage can easily be raised for transmission, so the current in the wires, and hence the heat $I^{2} R t$ wasted in them, is small, and it can be lowered again before use. (c) A fuse is a wire of low melting point connected in series in the live wire. In a short circuit the live and neutral wires touch, the resistance becomes very small and the current increases abruptly. This unduly high current heats the fuse wire (Joule heating) until it melts, which breaks the circuit and stops the current, so the circuit and the appliances are not damaged.

Step-by-step solution →
Q166 CBSE 2023
In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have
1. (a)higher power ratings such as geyser.
2. (b)lower power ratings such as fan.
3. (c)metallic bodies and low power ratings.
4. (d)non-metallic bodies and low power ratings.
Show answer

(a) higher power ratings such as geyser.

Step-by-step solution →
Q167 CBSE 2023
The correct pattern of magnetic field lines of the field produced by a current carrying circular loop is :
1. (a)Arcs above the axis with their arrowheads at the right, pointing right; arcs below the axis with their arrowheads at the left, pointing left; rings round both the top and the bottom of the loop, both circulating anticlockwise.
2. (b)Arcs above the axis with their arrowheads at the left, pointing left; arcs below the axis with their arrowheads at the right, pointing right; no rings round the loop.
3. (c)Arcs above and below the axis, all with their arrowheads at the left, pointing left; rings round the top of the loop circulating clockwise and rings round the bottom circulating anticlockwise.
4. (d)No arcs; large rings round the top of the loop circulating clockwise and round the bottom circulating anticlockwise.
Show answer

(c) Arcs above and below the axis, all with their arrowheads at the left, pointing left; rings round the top of the loop circulating clockwise and rings round the bottom circulating anticlockwise.

Step-by-step solution →
Q168 CBSE 2023
A constant current flows in a horizontal wire in the plane of the paper from east to west as shown in the figure. The direction of the magnetic field will be north to south at a point :
1. (a)directly above the wire.
2. (b)directly below the wire.
3. (c)located in the plane of the paper on the north side of the wire.
4. (d)located in the plane of the paper on the south side of the wire.
Show answer

(b) directly below the wire.

Step-by-step solution →
Q169 CBSE 2023
The magnetic field inside a long straight current carrying solenoid :
1. (a)is zero.
2. (b)decreases as we move towards its end.
3. (c)increases as we move towards its end.
4. (d)is same at all points.
Show answer

(d) is same at all points.

Step-by-step solution →
Q170 CBSE 2023
An electron projected towards east is deflected towards south by a uniform magnetic field. The direction of the magnetic field is :
1. (a)upwards
2. (b)downwards
3. (c)towards north
4. (d)towards west
Show answer

(b) downwards

Step-by-step solution →
Q171 CBSE 2023
According to the International colour coding, wires used in electrical appliances which require earthing are :
1. (a)Live is brown; Neutral is blue and Earth is black
2. (b)Live is brown; Neutral is blue and Earth is green
3. (c)Live is red; Neutral is green and Earth is blue
4. (d)Live is red; Neutral is green and Earth is black
Show answer

(b) Live is brown; Neutral is blue and Earth is green

Step-by-step solution →
Q172 CBSE 2023
An alpha particle enters a uniform magnetic field as shown. The direction of motion of the alpha particle is :
1. (a)towards right
2. (b)towards left
3. (c)into the page
4. (d)out of the page
Show answer

(d) out of the page

Step-by-step solution →
Q173 CBSE 2023
The resultant magnetic field at point 'P' situated midway between two parallel wires (placed horizontally) each carrying a steady current I is
1. (a)in the same direction as the current in the wires.
2. (b)in the vertically upward direction.
3. (c)zero
4. (d)in the vertically downward direction.
Show answer

(c) zero

Step-by-step solution →
Q174 CBSE 2023
A positron enters a uniform magnetic field at right angles to it as shown. The direction of force experienced by the positron will be :
1. (a)to the right
2. (b)to the left
3. (c)into the page
4. (d)out of the page
Show answer

(c) into the page

Step-by-step solution →
Q175 CBSE 2023
An alpha particle enters a uniform magnetic field as shown. The direction of force experienced by the alpha particle is :
1. (a)towards right
2. (b)towards left
3. (c)into the page
4. (d)out of the page
Show answer

(d) out of the page

Step-by-step solution →
Q176 CBSE 2023
For a current in a long straight solenoid, N and S poles are created at the two ends. Among the following statements, the incorrect statement is :
1. (a)The magnetic field lines inside the solenoid are in the form of straight lines, which indicates that the magnetic field is uniform at all points inside the solenoid.
2. (b)The strong magnetic field produced inside the solenoid can magnetize the soft iron placed inside it.
3. (c)The pattern of the magnetic field associated with a current carrying solenoid is different from the pattern of the magnetic field around a bar magnet.
4. (d)The N and S poles exchange positions when the direction of current through the solenoid is reversed.
Show answer

(c) The pattern of the magnetic field associated with a current carrying solenoid is different from the pattern of the magnetic field around a bar magnet.

Step-by-step solution →
Q177 CBSE 2023
A student has a long straight thick copper wire. If he passes a current in this wire he would get a magnetic field whose pattern must be :
1. (a)radial lines originating from the wire.
2. (b)concentric circles centred around the wire.
3. (c)straight lines parallel to the wire.
4. (d)straight lines perpendicular to the wire.
Show answer

(b) concentric circles centred around the wire.

Step-by-step solution →
Q178 CBSE 2023
The shape of magnetic field lines produced
1. (i)inside a solenoid
2. (ii)around a straight conductor, both carrying current of the same magnitude are, respectively :
1. (a)(i) straight, (ii) circular
2. (b)(i) circular, (ii) circular
3. (c)(i) straight, (ii) straight
4. (d)(i) circular, (ii) straight
Show answer

(a) (i) straight, (ii) circular

Step-by-step solution →
Q179 CBSE 2023
These consist of two statements – Assertion (A) and Reason (R). Answer this question selecting the appropriate option given below :
Assertion (A): The strength of the magnetic field produced at the centre of a current carrying circular coil increases on increasing the number of turns in it.
Reason (R): The current in each circular turn has the same direction and the magnetic field due to each turn then just adds up.
1. (a)Both (A) and (R) are true and (R) is the correct explanation of (A).
2. (b)Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (c)(A) is true, but (R) is false.
4. (d)(A) is false, but (R) is true.
Show answer

(a) Both (A) and (R) are true and (R) is the correct explanation of (A).

Step-by-step solution →
Q180 CBSE 2023
Two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to this question from the codes (a), (b), (c) and (d) as given below.
Assertion (A): Magnetic field lines do not intersect each other.
Reason (R): Magnetic field lines are imaginary lines, the tangent to which at any point gives the direction of the field at that point.
1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
3. (c)Assertion (A) is true, but Reason (R) is false.
4. (d)Assertion (A) is false, but Reason (R) is true.
Show answer

(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Step-by-step solution →