CBSE Class 10 Science — Magnetic Effects of Electric Current

Assertion (A): The needle of a magnetic compass kept in strong external magnetic field, always aligns itself in north-south direction on the earth. Reason (R): Behaviour of the needle of a compass is same as that of a freely suspended bar magnet.

(a) Describe an activity to show that a current carrying conductor, placed in an external magnetic field experiences a force. (b) Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally towards the front wall from the back wall, is deflected by a strong magnetic field to your right side. Find the direction of the magnetic field.

(a) The pattern of magnetic field due to a current carrying wire depends upon the shape made by that wire. Justify. (b) A current carrying straight wire AB is shown in the given diagram. Out of X, Y and Z on which point will the strength of magnetic field be maximum and why?

(A) (i) State the rule which gives the direction of force acting on the current carrying conductor placed in a uniform magnetic field. (ii) Name any two devices which work on the basis of an interaction between magnetic field and current carrying conductor. (iii) Comment on the magnitude of force on electron in both the cases and give reason for your answer. OR (B) (i) List three possible reasons of short-circuiting in an electric circuit. (ii) In case of overload, will the fuse protect to given electric circuit from damage? Justify your answer. (iii) For an electric heater rated as 220 V, 2200 W, what should be the minimum rating of fuse used with it?

Which one of the following statements is not true about a bar magnet ?

The strength of magnetic field produced inside a long straight current carrying solenoid does not depend upon :

Assertion (A) : The pattern of the magnetic field of a solenoid carrying a current is similar to that of a bar magnet. Reason (R) : The pattern of the magnetic field around a current carrying conductor is independent of the shape of the conductor.

Assertion (A): Magnetic field lines around a bar magnet never intersect each other. Reason (R): Magnetic field produced by a bar magnet is a quantity that has both magnitude and direction.

Assertion (A) : No two magnetic field lines are found to cross each other. Reason (R) : The compass needle cannot point towards two directions at the point of intersection of two magnetic field lines.

What are magnetic field lines. List two important properties of magnetic field lines.

Consider a rectangular cardboard having two holes P and Q through which a current carrying circular loop has been inserted as shown in the diagram. (a) Make this diagram on your answer sheet and draw three magnetic field lines, one each passing through the points 1 (near P), 2 (at the centre of the loop) and 3 (near Q). (b) List two factors on which the intensity of the magnetic field produced at the centre of the loop depends. (c) Name the rule you will apply to determine the direction of magnetic field produced due to a current carrying straight conductor.

(a) What are magnetic field lines? How is the direction of magnetic field at a point determined? Draw the pattern of magnetic field lines of the magnetic field produced by a current carrying circular loop. Mark on it the direction of (i) current and (ii) magnetic field lines. Name the two factors on which the magnitude of the magnetic field due to a current carrying coil depends. OR (b) Why can't two magnetic field lines cross each other? Draw magnetic field lines showing the direction of the magnetic field due to a current carrying long straight solenoid. State the conclusion which can be drawn from the pattern of magnetic field lines inside the solenoid. Name any two factors on which the magnitude of the magnetic field due to this solenoid depends.

(A) (i) Draw the pattern of the magnetic field lines for the two parallel straight conductors carrying current of same magnitude 'I' in opposite directions as shown. Show the direction of magnetic field at a point O which is equidistant from the two conductors. (Consider that the conductors are inserted normal to the plane of a rectangular cardboard.) (ii) In our houses we receive A.C. electric power of $220\text{ V}$. In electric iron or electric heater cables having three wires with insulation of three different colours - red, black and green are used to draw current from the mains. (a) What are these three different wires called? Name them colourwise. (b) What is the potential difference between the red wire and the black wire? (c) What is the role of the wire with green insulation in case of accidental leakage of electric current to the metallic body of an electrical appliance? OR (B) (i) By using the given experimental set-up. How can it be shown that: (a) a force is exerted on the current-carrying conductor AB when it is placed in a magnetic field. (b) the direction of force can be reversed in two ways. (ii) When will the magnitude of the force be highest? (iii) State Fleming's left hand rule.

(a) The given figure shows the current passing through the straight conductor XY. (i) Copy the diagram and draw the magnetic field lines when current flows from conductor X to Y. (ii) Name and state the rule used in determining the direction of the magnetic field lines in the situation given above. (iii) State Fleming's left hand rule. Using this rule, determine the direction of force applied on an electron entering a uniform magnetic field as shown in the figure. OR (b) (i) Define the term solenoid. Draw the pattern of the magnetic field lines in and around a current carrying straight solenoid. Mark on the pattern the (i) direction of current, (ii) direction of field lines near the ends of the solenoid, and (iii) region where the magnetic field is uniform. (ii) How would you make an electromagnet using a current carrying solenoid?

In order to obtain magnetic field lines around a bar magnet, a student performed an experiment using a magnetic compass and a bar magnet. The magnet was placed on a sheet of white paper fixed on a drawing board. Using magnetic needle he obtained on the paper a pattern of magnetic field lines around the bar magnet. (a) By convention, the field lines emerge from north pole and merge at south pole. Why? Give reason. (b) State the relationship between strength of the magnetic field and the degree of closeness of the field lines. (c) (A) (i) No two field lines can ever intersect each other. Give reason. (ii) The magnetic field in a given region is uniform. Draw a diagram to represent it. OR (c) (B) Draw the pattern of the magnetic field lines through and around a current carrying solenoid. What does the pattern of field lines inside the solenoid represent?

The pattern of the magnetic field produced inside a current carrying solenoid is :

The current carrying device which produces a magnetic field similar to that of a bar magnet is :

A rectangular loop ABCD carrying a current I is situated near a straight conductor XY, such that the conductor is parallel to the side AB of the loop and is in the plane of the loop. If a steady current I is established in the conductor as shown, the conductor XY will

Strength of magnetic field produced by a current carrying solenoid DOES NOT depend upon :

Assertion (A): Magnetic field lines never intersect each other. Reason (R): If they intersect, then at the point of intersection, the compass needle would point towards two directions, which is not possible.

Assertion (A) : The deflection of a compass needle placed near a current carrying wire decreases when the magnitude of an electric current in the wire is increased. Reason (R) : Strength of the magnetic field at a point due to a current carrying conductor increases on increasing the current in the conductor.

(a) Draw a labelled diagram to show the pattern of magnetic field lines produced due to a current carrying straight conductor. Mark on it the direction of current in the conductor and the direction of magnetic field lines. OR (b) Name the device used to magnetise a piece of magnetic material. Draw a labelled diagram to show the arrangement used for the magnetisation of a cylinder made of soft iron.

(i) Two magnetic field lines do not intersect each other. Why ? (ii) How is a uniform magnetic field in a given region represented ? Draw a diagram in support of your answer.

Draw a diagram to show the pattern of magnetic field lines on a horizontal sheet of paper due to a straight conductor passing through its centre and carrying current vertically upwards. Mark on it (i) the direction of current in the conductor and (ii) the corresponding magnetic field lines. State right hand thumb rule and check whether the directions marked by you are in accordance with this rule or not.

Name and state the rule to determine the direction of a : (i) magnetic field produced around a current carrying straight conductor. (ii) force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it.

A student fixes a sheet of white paper on a drawing board. He places a bar magnet in the centre of it. He sprinkles some iron filings uniformly around the bar magnet. Then he taps the drawing board gently and observes that the iron filings arrange themselves in a particular pattern. (a) Why do iron filings arrange in a particular pattern? (b) What does the crowding of iron filings at the ends of the magnet indicate? (c) What do the lines, along which the iron filings align, represent? (d) If the student places a cardboard horizontally in a current carrying solenoid and repeats the above activity, in what pattern would the iron filings arrange ? State the conclusion drawn about the magnetic field based on the observed pattern of the lines.

(a) What happens when a bundle of wires of soft iron is placed inside the coil of a solenoid carrying a steady current? Name the device obtained. Why is it called so? (b) Draw the magnetic field lines inside a current carrying solenoid. What does this pattern of magnetic field lines indicate?

Explain in brief the function of an electric fuse in a domestic circuit. An electric heater of current rating 3 kW; 220 V is to be operated in an electric circuit of rating 5 A. What is likely to happen when the heater is switched 'ON'? Justify your answer with necessary calculation.

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:

The correct pattern of magnetic field lines of the field produced by a current carrying circular loop is :

In domestic electric circuits the wiring with 15 A current rating is for the electric devices which have

The magnetic field inside a long straight current carrying solenoid:

An alpha particle enters a uniform magnetic field as shown. The direction of force experienced by the alpha particle is :

The resultant magnetic field at point 'P' situated midway between two parallel wires (placed horizontally) each carrying a steady current I is

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 :

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.

Assertion (A) : Two magnetic field lines around a current carrying straight wire do not intersect each other. Reason (R) : The magnitude of the magnetic field produced at a given point increases as the current through the wire increases.

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.

Assertion (A) : A current carrying straight conductor experiences a force when placed perpendicular to the direction of magnetic field. Reason (R) : The net charge on a current carrying conductor is always zero.

State the rule to determine the direction of a (a) magnetic field produced around a straight conductor carrying current and (b) force experienced by a current carrying straight conductor placed in a magnetic field which is perpendicular to it.

What is a solenoid? When does a solenoid behave as a magnet? Draw the pattern of the magnetic field produced inside it showing the directions of the magnetic field lines.

(a) (i) State the rule used to find the force acting on a current carrying conductor placed in a magnetic field. (ii) Given below are three diagrams showing entry of an electron in a magnetic field. Identify the case in which the force will be (1) maximum and (2) minimum respectively. Give reason for your answer. OR (b) (i) Draw the pattern of magnetic field lines of (1) a current carrying solenoid (2) a bar magnet (ii) List two distinguishing features between the two fields.

(A) (i) Why is an alternating current (A.C.) considered to be advantageous over direct current (D.C.) for the long distance transmission of electric power? (ii) How is the type of current used in household supply different from the one given by a battery of dry cells? (iii) How does an electric fuse prevent the electric circuit and the appliances from a possible damage due to short circuiting or overloading. OR (B) For the current carrying solenoid as shown, draw magnetic field lines and give reason to explain that out of the three points A, B and C, at which point the field strength is maximum and at which point it is minimum?

(a) (i) A straight cylindrical conductor is suspended with its axis perpendicular to the magnetic field of a horse-shoe magnet. The conductor gets displaced towards left when a current is passed through it. What will happen to the displacement of the conductor if the (1) current through it is increased? (2) horse-shoe magnet is replaced by another stronger horse-shoe magnet? (3) direction of current through it is reversed? (ii) Name and state the rule for determining the direction of force on a current carrying conductor in a magnetic field. OR (b) Draw the pattern of the magnetic field produced around a vertical current carrying straight conductor passing through a horizontal cardboard. Mark the direction of current and the magnetic field lines. Name and state the rule which is used to determine the direction of magnetic field associated with a current carrying conductor.

As shown in the diagram an aluminium rod 'AB' is suspended horizontally between the two poles of a strong horse shoe magnet in such a way that the axis of rod is horizontal and the direction of the magnetic field is vertically upward. The rod is connected in series with a battery and a key. State giving reason: (a) What is observed when a current is passed through the aluminum rod from end B to end A? (b) What change is observed in a situation in which the axis of the rod 'AB' is moved and aligned parallel to the magnetic field and current is passed in the rod in the same direction? OR "Magnetic field is a physical quantity that has both direction and magnitude." How can this statement be proved with the help of magnetic field lines of a bar magnet?

(a) Name the poles P, Q, R and S of the magnets in the following figures 'a' and 'b'. (b) State the inference drawn about the direction of the magnetic field lines on the basis of these diagrams.

(a) (i) Name and state the rule to determine the direction of force experienced by a current carrying straight conductor placed in a uniform magnetic field which is perpendicular to it. (ii) An alpha particle while passing through a magnetic field gets projected towards north. In which direction will an electron project when it passes through the same magnetic field ? OR (b) (i) What is a solenoid ? (ii) Draw the pattern of magnetic field lines of the magnetic field produced by a solenoid through which a steady current flows.

OR When is the force experienced by a current - carrying straight conductor placed in a uniform magnetic field (i) Maximum; (ii) Minimum ?

What is a Solenoid? Draw the pattern of the magnetic field lines around a current carrying solenoid. Mark on the pattern the region where the magnetic field is uniform.

(b) In the figure given below, a simple electric motor is shown: As shown in the figure, the current in the coil $ABCD$ flows from A to B in the arm $AB$ and C to D in the arm $CD$. (i) State the directions in which the arms $AB$ and $CD$ will experience a force. (ii) Identify the part of the electric motor that reverses the flow of current in the coil $ABCD$ and write its name. (iii) After the reversal of flow of current in the coil $ABCD$, state the directions in which the arms $AB$ and $CD$ will experience a force. (iv) Name the rule which is applied to determine the direction of force on a current carrying conductor placed in a magnetic field.

(a) In the diagram given below, Coil - 1 is connected in series with a battery and a plug key while Coil - 2 is connected with a galvanometer. (i) Why does the galvanometer show deflection only when the key (K) is plugged in and not when a steady current starts flowing in the circuit? (ii) What is observed in the galvanometer, when the key is plugged out? (iii) State the conclusion based on the observation of this activity.

AB is a coil of copper wire having a large number of turns. The ends of the coil are connected with a galvanometer as shown. When the north pole of a strong bar magnet is moved towards the end B of the coil, a deflection is observed in the galvanometer. (a) State the reason for using galvanometer in the activity and why does its needle deflects momentarily when magnet is moved towards the coil. (b) What would be observed in the galvanometer in a situation when the coil and the bar magnet both move with the same speed in the same direction? Justify your answer. (c) State the conclusion that can be drawn from this activity. Will there be any change in the momentary deflection in the galvanometer if number of turns in the coil is increased and a more stronger magnet is moved towards the coil? OR What is electromagnetic induction? What is observed in the galvanometer when a strong bar magnet is held stationary near one end of a coil of large number of turns? Justify your answer.

A student was asked to perform an experiment to study the force on a current carrying conductor in a magnetic field. He took a small aluminum rod AB, a strong horse shoe magnet, some connecting wires, a battery and a switch and connected them as shown. He observed that on passing current, the rod gets displaced. On reversing the direction of current, the direction of displacement also gets reversed. On the basis of your understanding of this phenomenon, answer the following questions: (a) Why does the rod get displaced on passing current through it? (b) State the rule that determines the direction of the force on the conductor AB. (c) (i) If the U shaped magnet is held vertically and the aluminum rod is suspended horizontally with its end B towards due north, then on passing current through the rod from B to A as shown, in which direction will the rod be displaced? (ii) Name any two devices that use current carrying conductors and magnetic field.

A student fixes a sheet of white paper on a drawing board using some adhesive materials. She places a bar magnet in the centre of it and sprinkles some iron filings uniformly around the bar magnet using a salt-sprinkler. On tapping the board gently, she observes that the iron filings have arranged themselves in a particular pattern. (a) Draw a diagram to show this pattern of iron filings. (b) Draw the magnetic field lines of a bar magnet showing the poles of the bar magnet as well as the direction of the magnetic field lines. (c) (i) How is the direction of magnetic field at a point determined using the field lines? Why do two magnetic field lines not cross each other? OR (ii) How are the magnetic field lines of a bar magnet drawn using a small compass needle? Draw one magnetic field line each on both sides of the magnet.

OR (for part c) Draw the pattern of magnetic field lines produced around a current carrying straight conductor held vertically on a horizontal cardboard. Indicate the direction of the field lines as well as the direction of current flowing through the conductor.

The change in magnetic field lines in a coil is the cause of induced electric current in it. Name the underlying phenomenon.

(b) Name two countries, other than India, where power plants based on geothermal energy are operational.

(d) State an important advantage of using AC over DC.

(c) Name the phenomenon that explains the working of an electric generator.

(a) What are geothermal energy hot-spots?

Fleming's Right-hand rule gives

(a) A coil of insulated wire is connected to a galvanometer. What would be observed if a strong bar magnet with its south pole towards one face of the coil is (i) moved quickly toward it? (ii) moved quickly away from it? (iii) held stationary near it? (b) Name the phenomena involved. (c) State the conclusion based on the observations in (i), (ii) and (iii).

Give reasons for the following : (i) There is either a convergence or a divergence of magnetic field lines near the ends of a current carrying straight solenoid. (ii) The current carrying solenoid when suspended freely rests along a particular direction. (iii) The burnt out fuse should be replaced by another fuse of identical rating.

Two coils of insulated copper wire are wound over a non-conducting cylinder as shown. Coil 1 has comparative large number of turns. State your observations, when (i) Key K is closed. (ii) Key K is opened. Give reason for each of your observations.

(a) What is an electromagnet? List any two uses. (b) Draw a labelled diagram to show how an electromagnet is made. (c) State the purpose of soft iron core used in making an electromagnet. (d) List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.

(a) State Fleming's Left-hand rule. (b) List three characteristic features of the electric current used in our homes. (c) What is a fuse? Why is it called a safety device? (d) Why is it necessary to earth metallic electric appliances?

What is the function of a galvanometer in a circuit?

What is a solenoid? Draw the pattern of magnetic field lines of (i) a current carrying solenoid and (ii) a bar magnet. List two distinguishing features between the two fields.

(a) Draw magnetic field lines of a bar magnet. "Two magnetic field lines never intersect each other." Why? (b) An electric oven of $1.5\text{ kW}$ is operated in a domestic circuit ($220\text{ V}$) that has a current rating of $5\text{ A}$. What result do you expect in this case? Explain.

A charged particle enters at right angles into a uniform magnetic field as shown. What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to its interaction with the magnetic field ?

What is a solenoid ? Draw the pattern of magnetic field lines of a solenoid through which a steady current flows. What does the pattern of field lines inside the solenoid indicate ?

A coil of insulated wire is connected to a galvanometer. What would be seen if a bar magnet with its north pole towards one face of the coil is (i) moved quickly towards it, (ii) moved quickly away from the coil and (iii) placed near its one face ? Name the phenomena involved.