Contents
- 1 Class 10 Science Chapter 13 Important Questions with Answers Magnetic Effects of Electric Current
- 1.1 Magnetic Effects of Electric Current Class 10 Important Questions Very Short Answer Type
- 1.2 Magnetic Effects of Electric Current Class 10 Important Questions Short Answer Type I
- 1.3 Magnetic Effects of Electric Current Class 10 Important Questions Short Answer Type II
- 1.4 Magnetic Effects of Electric Current Class 10 Important Questions Long Answer Type
Solved the very best collection of Magnetic Effects of Electric Current Class 10 Science Important Questions and Answers Chapter 13 Pdf from the latest NCERT edition books, It will help you in scoring more marks in CBSE Exams.
Class 10 Science Chapter 13 Important Questions with Answers Magnetic Effects of Electric Current
Class 10 Chemistry Chapter 13 Important Questions with Answers Magnetic Effects of Electric Current
Magnetic Effects of Electric Current Class 10 Important Questions Very Short Answer Type
Question 1.
Mention the angle between a current carrying conductor and magnetic field for which the force experienced by this current carrying conductor placed in magnetic field is largest? (2012)
Answer:
The force is the largest, when angle between the current carrying conductor and magnetic field direction is a right angle, i.e., 90°.
Question 2.
Name the physical quantities which are indicated by the direction of thumb and forefinger in Fleming’s right-hand rule? (2012)
Answer:
In Fleming’s right-hand rule, forefinger points in the direction of magnetic field and thumb points in the direction of motion of conductor.
Question 3.
Write any one method to induce current in a coil. (2013)
Answer:
A current is induced in a coil when it is moved (or rotated) relative to a fixed magnet.
Magnetic Effects of Electric Current Class 10 Important Questions Short Answer Type I
Question 1.
List the properties of magnetic lines of force. (2017 OD)
Answer:
- These field lines start from N pole and end at S pole of the magnet.
- These lines never intersect each other.
- The tangent at any point on the magnetic line gives the direction of magnetic field at that point.
- The magnetic field lines of a magnet form a continuous closed loop.
Magnetic Effects of Electric Current Class 10 Important Questions Short Answer Type II
Question 1.
(a) Draw magnetic field lines produced around a current carrying straight conductor passing through cardboard. How will the strength of the magnetic field change, when the point where magnetic field is to be determined, is moved away from the straight wire carrying constant current ? Justify your answer.
(b) Two circular coils A and B are placed close to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
Answer:
(a) (i) The magnetic field lines around a straight conductor carrying resistance current are concentric circles whose centre lies on the wire.
(ii) When a point where magnetic field is to be determined is moved away from the straight wire, the strength of the magnetic field decreases because as we move away from a current carrying straight conductor, the concentric circles around it representing magnetic field lines become larger and larger indicating the decreasing strength of magnetic field.
(b) Yes, current is induced in the coil B. Because as the current in the coil A changes, the magnetic field lines around the coil B also change. Therefore, the change in magnetic field lines associated with the coil B is the cause of induced electric current in it.
Question 2.
(i) State Maxwell’s right-hand thumb rule.
(ii) PQ is a current carrying conductor in the plane of the paper as shown in the figure. Mention the direction of magnetic fields produced by it at points A and B. Given r1 < r2, where will the strength of the magnetic field be larger? (2012)
Answer:
(i) Maxwell’s right hand thumb rule. The direction of the current is given by Maxwell’s right hand thumb rule, “If the current carrying conductor is gripped with the right hand in such a way that the thumb gives the direction of the current, then the direction of the fingers gives the direction of the magnetic field produced around the conductor”.
(ii) Since the direction of current in the straight conductor is from Q to P, then according to Maxwell’s right hand thumb rule, magnetic field at point A is inside the paper and at point B is outside the paper. Since r1 < r2 the strength of the magnetic field at A is more than at B because greater the distance of a point from the current carrying wire, weaker will be the magnetic field produced at that point.
Question 3.
(a) Shruti draws magnetic field lines close to the axis of a current carrying circular loop. As she moves away from the centre of circular loop, she observes that the lines keep on diverging. Explain the reason for her observation.
(b) Write two properties of magnetic field lines.
Answer:
(a) The pattern of magnetic field due to current carrying circular loop are circular near the current carrying loop but the concentric circles representing magnetic field lines become bigger and bigger. At the centre of the circular loop, the magnetic field lines are straight. Therefore on moving away from the centre of circular loop, magnetic field lines keep on diverging.
(b) Properties of magnetic field lines:
- These lines originate from the north pole and end at the south pole.
- Two magnetic field lines do not intersect each other.
Question 4.
(a) Describe an activity to show with the help of a compass that magnetic field is strongest near poles of a bar magnet.
(b) Mention the direction of magnetic field lines (i) inside a bar magnet and (ii) outside a bar magnet. (2013)
Answer:
(a) A bar magnet is placed on a sheet of paper and its boundary is marked with a pencil. A magnetic compass is brought near the N-pole of the bar magnet. It is observed that N-pole of magnet repels the N-pole of compass needle due to which the tip of the compass needle moves away from the N-pole. Thus a magnetic field pattern is obtained around a bar magnet. Each magnetic field line is directed from the north pole of a magnet to its south pole. The field lines are closest together at the two poles of the bar magnet. The strength of magnetic field is indicated by the degree of closeness of the field lines. So the magnetic field is the strongest near the poles.
(b) (i) The direction of magnetic field lines inside a bar magnet is from its south pole to its north pole.
(ii) The direction of magnetic field lines outside a bar magnet is from its north pole to its
south pole.
Question 5.
Explain the effect on the magnetic field produced at a point in a current carrying circular coil due to:
(i) increase in the amount of current flowing through it
(ii) increase in the distance of point from the coil
(iii) increase in the number of turns of the coil. (2013)
Answer:
(i) The magnitude of magnetic field produced by a current carrying circular coil at a point is directly proportional to the current flowing through the circular coil. Thus as the amount of current flowing through the circular coil increases, the magnetic field produced at a point in a circular coil increases.
(ii) Magnitude of magnetic field produced at a point in a current carrying circular coil is inversely proportional to the distance of point from the coil. Thus the magnetic field produced at a point decreases as the distance increases from the coil.
(iii) The magnetic field produced by a current carrying wire at a given point depends directly on the cur¬rent passing through it. Therefore, if there is a circular coil having n turns, the field produced is n times as large as that produced by a single turn. This is because the current in each circular turn has the same direction, and the field due to such turns then just adds up.
Question 6.
What are magnetic field lines? List two characteristic properties of these lines. (2014)
Answer:
Magnetic field lines are the lines drawn in a magnetic field along which north magnetic pole would move. The direction of a magnetic field at a point is determined with the help of a small magnetic compass. When a compass is moved along the magnetic line, then the line drawn from the south pole of the compass to its north pole indicates the direction of the magnetic field.
Properties of magnetic lines of force:
- The magnetic lines originate from the north pole and end at the south pole.
- The magnetic field lines of a magnet form a continuous closed loop.
- The magnetic lines of force do not intersect each other.
Question 7.
Draw the pattern of magnetic field lines around a current carrying straight conductor. How does the strength of the magnetic field produced change:
(i) with the distance from the conductor?
(ii) with an increase in current in a conductor? (2015)
Answer:
(i) Strength of the magnetic field produced by a straight current carrying wire at a point is inversely proportional to the distance of that point from the wire.
(ii) Strength of the magnetic field is directly proportional to the current passing in the wire.
Question 8.
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? (2017 D)
Answer:
(i) When the north pole (N) of the magnet is pushed into the coil, the galvanometer is deflected towards the right.
(ii) When the north pole (N) of the magnet is withdrawn from the coil, the galvanometer is deflected towards the left.
(iii) When the magnet is held stationary inside the coil, the deflection of the galvanometer is zero.
Question 9.
Draw a sketch of the pattern of field lines due to a:
(a) current flowing into a circular coil,
(b) solenoid carrying current. (2017 OD)
Answer:
(a)
(b)
Magnetic Effects of Electric Current Class 10 Important Questions Long Answer Type
Question 1.
(a) With the help of a labelled diagram, describe an activity to show that a current carrying conductor experiences a force when placed in a magnetic field. Mention the position when this force is maximum.
(b) Name and state the rule which gives the direction of force acting on the conductor. (2012, 2015)
Answer:
(a) Activity:
- A small aluminium rod (AB) about 5 cm is suspended with two connecting wires horizontally from a stand.
- A strong horseshoe magnet is placed in such a way that the rod lies between the two poles with the magnetic field directed upwards, the north pole of the magnet vertically below and south pole vertically above the aluminium rod arranged.
- The aluminium rod is connected in series with a battery, a key and a rheostat.
- When a current is allowed to pass through aluminium rod from end B to end A, it is observed that the rod is displaced towards the left.
- When the direction of the current is reversed from A to B, it is observed that the direction of displacement of the rod is towards the right.
This activity shows that when a current carrying conductor is placed in a magnetic field, a mechanical force is exerted on the conductor which makes it move.
The maximum force is exerted on a current carrying conductor only when it is perpendicular to the direction of magnetic field.
(b) The direction of force acting on the current carrying conductor can be found out by using Fleming’s left-hand rule. According to Fleming’s left-hand rule, hold the forefinger, the centre finger and the thumb of your left hand at right angles to one another. Adjust your hand in such a way that the forefinger points in the direction of magnetic field and the centre finger points in the direction of current, then the direction in which thumb points, gives the direction of force acting on the conductor.
Question 2.
(a) Draw magnetic field lines of a bar magnet. “Two magnetic field lines never intersect each other.” Why?
(b) An electric oven of 1.5 kW is operated in a domestic circuit (220 V) that has a current rating of 5 A. What result do you expect in this case? Explain. (2014)
Answer:
(a) Two magnetic field lines do not intersect one another. The direction of magnetic field lines is always from north pole to south pole. If the two magnetic field lines do intersect, it means at the point of intersection the compass needle is showing two different directions which is not possible.
(b) Power, P= 1.5 kW = 1.5 × 1,000 = 1,500 W
Voltage, V = 220 V, I = ?
P = V × I ⇒ I = \(\frac{P}{V}=\frac{1,500}{220}\) = 6.8 A
Now the current drawn by the oven is 6.8 A which is very high but the fuse in this circuit is only 5 A capacity. When a very high current of 6.8 A flows through 5 A fuse, the fuse wire will get heated too much, melt and break the circuit, cutting off the power supply.
Question 3.
(a) A coil of insulated wire is connected to a galvanometer. What would be seen if a bar magnet with its south pole towards one face of the coil is (2015)
(i) moved quickly toward it
(ii) moved quickly away from it
(iii) placed near its one face?
These activities are then repeated with north pole of the magnet. What will be the observations?
(b) Name and define the phenomenon involved in above activities.
(c) Name the rule which can determine the direction of current in each case.
Answer:
(a) A coil of insulated wire is connected to a galvanometer and if a bar magnet with its south pole towards one face of the coil is
(i) moved quickly towards it, the galvanometer is deflected towards the left.
(ii) moved quickly away from it, the galvanometer is deflected towards the right.
(iii) placed near its one face, the deflection of the galvanometer is zero.
If this activity is repeated with north pole of the magnet –
(i) If the magnet is pushed into the coil, the galvanometer is deflected towards the right.
(ii) If the magnet is withdrawn from the coil, the galvanometer is deflected towards the left.
(iii) If the magnet is held stationary inside the coil, the deflection of the galvanometer is zero.
(b) This phenomenon involved in this activity is ‘Electromagnetic Induction’. The production of electric current by moving a magnet inside a fixed coil of wire is called electromagnetic induction.
(c) The direction of induced current is determined by ‘Fleming’s Right Hand Rule’.
Question 4.
(a) Define electromagnetic induction.
(b) Two coils P and S are wound over the same iron core. Coil P is connected to battery and key and the coil S is connected to galvanometer. Draw a suitable diagram of this arrangement and write your observations when:
(i) Current in the coil P is started by closing the key.
(ii) Current continues to flow in coil P.
(iii) Current in coil P is stopped by removing the key.
(iv) Explain the reason for such observations. (2012)
Answer:
(a) The production of electricity from magnetism is called electromagnetic induction.
- The current produced by moving a straight wire in a magnetic field is called induced current.
- The phenomenon of electromagnetic induction was discovered by a British Scientist Michael Faraday.
- A galvanometer is an instrument which can detect the induced current in a circuit.
(b) (i) As the current in the coil P is started by closing the key, it is observed that the needle of the galvanometer instantly jumps to one side and just as quickly returns to zero indicating a momentary current in coil (S).
(ii) If the current continues to flow in coil (P) then nothing will happen in the galvanometer of coil (S).
(iii) If current in coil (P) is stopped by removing the key then the needle of the galvanometer momentarily moves but to the opposite side.
(iv) Conclusion. Whenever the current in coil P is changing (starting or stopping) then an electric current is induced in the nearby coil S. Coil P, which causes induction, is called primary coil whereas coil S in which current is induced is called secondary coil.
- When the switch is on, current starts passing through coil P. It becomes an electromagnet and produces a magnetic field around coil S. So an induced current flows in coil S for a moment.
- When the current in coil P becomes steady, its magnetic field also becomes steady and the current in coil S stops.
- When we switch off the current in coil P, its magnetic field in coil S stops quickly. This effect is just the same as pulling a magnet quickly out of coil S. So an induced current flows in coil S but in the opposite direction.