CBSE Class 10 Physics Magnetic Effects Of Electric Current Worksheet Set B

Question : Name the type of current: (a) used in household supply. (b) given by a cell.
Answer : (a) Alternating current. (b) Direct current.

Question : Name any two appliances which are based on the application of heating effect of electric current.
Answer :Room heater and geyser.

Question : Give one difference between the wires used in the element of an electric heater and in a fuse.
Answer : Electric wire used in electric heater has a high melting point whereas fuse wire has a low melting point

Question : Identify the poles of the magnet in the given figure.

Answer : Both the poles facing each other represent south pole in nature as the magnetic field lines outside the magnet move from North to South Poles.

Question : State the direction of magnetic field in the following case.

Answer : In given situation, according to Fleming’s Left-Hand Rule Force is along y-axis. Current is along x-axis. Then magnetic field is along z-axis.

Question : State the direction of magnetic field in the following case.

Answer : Perpendicular to the plane of paper in the outward direction by using Fleming’s left hand rule.

Question : State the observation made by Oersted on the basis of his experiment with current carrying  conductors.
Answer : The electric current passing through a conducting wire produces magnetic effect.

Question : Name the physical quantities which are indicated by the direction of thumb and forefinger in the Fleming’s right hand rule?
Answer : In Fleming’s right hand rule, thumb indicates — direction of motion of the conductor; forefinger indicates — direction of magnetic field.

Question : A positively charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards north (b) towards east
(c) downward (d) upward
Answer : (d) Upward (Apply Fleming’s left hand rule).

Question : A steady current of 5 A is flowing through a conductor AB. Will the current be induced in the circular wire of radius lm?

Answer : No, because circular coil is placed in a constant magnetic field produced by a steady current of 5A.

Question : The diagram shows a coil of wire wound on a soft iron core forming an electromagnet. A current is passed through the coil in the direction indicated by the arrows. Mark the N and S poles produced in the iron core.

Answer : Using clock face rule A is South pole. B is North pole.

Question : How will you determine the direction of the magnetic field due to a current-carrying solenoid in the below diagram?

Answer : Direction of magnetic field: Imagine the current carrying solenoid in your right hand such that the curled fingers are in the direction of current, then the extended thumb will indicate the direction of emerging magnetic field line, i.e. the face of solenoid which has North polarity.

Question : Name the device used to prevent damage to the electrical appliances and the domestic circuit due to overloading.
Answer : Electric fuse.

Question : A current carrying straight wire held perpendicular to the plane of paper and current passes through this conductor in the vertically upward direction. What is the direction of magnetic field produced around it?
Answer : According to right-hand thumb rule, the direction of magnetic field produced around the given conductor is anticlockwise.

Question : Give one application of electromagnetic induction.
Answer : This phenomenon is used in electric generator

Question : The diagram shows a beam of electrons about to enter a magnetic field. The direction of the field is into the page.

What will be the direction of deflection, if any, as the beam passes through the field?
Answer : Direction of current is from right to left as electron beam enters from left to right and magnetic field is into the page. So, according to Fleming’s left hand rule, force is perpendicular to the flow of current and in its left side. So, electron beam deflects towards bottom of the page.

Question : How can you show that the magnetic field produced by a given electric current in the wire decreases as the distance from the wire increases?
Answer : The decrease in deflection of the magnetic compass needle clearly shows that the magnetic field decreases as we move away from the current-carrying conductor.

Question : Name the device which is used to draw magnetic field lines.
Answer : Compass needle.

Question : If the circular coil has n turns, the field produced is n times as large as that produced by a single turn. Justify it.
Answer : This is because the current in each circular turn has the same direction, and the field due to each turn then just adds up along the axis of the coil

Question : A charged particle enters at right angle 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?

Answer : Using Fleming’s left hand rule, the nature of charged particle is positive.

Question : An electron beam is moving vertically upwards. If it passes through a magnetic field which is directed from south to north in a horizontal plane, then in which direction will the beam deflect?
Answer : Using Fleming’s Left-Hand Rule, electron beam will be deflected towards the west.

Short Answers

Question : Identify the type of magnetic field represented by the magnetic field lines given below and name the type of conductors which can produce them.
Answer : (a) These magnetic field lines are produced by a current carrying loop.
(b) These are magnetic field lines produced by solenoid

Question : How is the strength of magnetic field near a straight current-carrying conductor
(i) related to the strength of current in the conductor?
(ii) is affected when the direction of flow of current is reversed?
Answer : (i) The strength of magnetic field is directly proportional to the strength of current.
(ii) If we reverse the direction of current, the direction of magnetic field will also be reversed.

Question : Can a freely suspended current carrying solenoid stay in any direction? Justify your answer. What will happen when the direction of current in the solenoid is reversed? Explain.
Answer : A current carrying solenoid behaves like a bar magnet. When it is suspended freely it will stay in north–south direction. On reversing the direction current, it will turn to 180°° because its polarity will be reversed.

Question : State two ways by which the strength of an electromagnet is increased.
Answer : (i) Increase in number of turns in the solenoid.
(ii) Increase in the strength of current flowing in the solenoid

Answer : Describe an activity to show magnetic field lines are produced when current is passed through circular coil.
Answer : (i) Take a rectangular cardboard having two holes.
(ii) Insert a circular coil through these holes, normal to the plane of paper.
(iii) Connect the ends of coil in series with a battery, and key. 
(iv) Sprinkle iron filings uniformly on the cardboard.
(v) Plug the key.
(vi) Tap the cardboard gently a few times. Note the pattern of the iron filings.
(vii) The pattern of magnetic field lines will be same as the pattern of iron filings.

Question : A uniform magnetic field is directed vertically upwards. In which direction in this field forces an particle (+ve charged) be projected to that it is deflected southward? Name and state the rule you have to use to find the direction in this force.
Answer : The direction of motion of particles is from west to east. Fleming’s left hand rule is used to find the direction of force.

Question : (i) A compass needle gets deflected when brought near a current carrying conductor. Why?
(ii) What happens to the deflection of needle when current in the conductor is increased?
Answer : (i) It is because current carrying conductor produces a magnetic field which superimposes with magnetic field of compass needle due to which needle of compass gets deflected.
(ii) The deflection in the magnetic needle will increase as the strength of current increases.

Question : Define a solenoid. Compare the magnetic field produced by a solenoid with that of a bar magnet.
Answer : A coil of many circular turns of copper wire wrapped in the shape of a cylinder, is called a solenoid. The magnetic field lines in a solenoid, through which current is passed, is very similar to that of a bar magnet. One end of the coil acts like the magnetic north pole, while the other acts like the magnetic south pole. The magnetic field produced by a long solenoid has all the properties of the field produced by a bar magnet.

Question : An alpha particle (positively charged) enters a magnetic field at right angle to it as shown in figure. Explain with the help of relevant rule, the direction of force acting on the alpha particle.
Answer : The force will act in upward direction given by thumb, if forefinger points in the direction of magnetic field and the middle finger points in the direction of current, according to Fleming’s left hand rule.

Question : List three sources of magnetic field.
Answer : (i) Magnetic field is associated with bar magnet
(ii) A current carrying conductor produces magnetic field.
(iii) A current carrying curricular loop also produces magnetic field.

Question : You are given three identical looking bars one of which is a magnet, the other made of a magnetic material and the third made of a non magnetic material. Using just these three bars how will you find out which is which?
Answer : Bring one bar close to the other two one by one: if the bar attracts one of these and does not attract the other one, the bar which is not attracted is made of non-magnetic material and the bar in our hand is a magnet or a bar of magnetic material. Keep one bar on the table and move other bar along its length from one end to the other, if uniform attraction is felt the bar in our hand is a magnet and vice versa.

Question : Write one application for each of the following:
(a) Right-hand Thumb Rule,
(b) Fleming’s left Hand Rule,
(c) Fleming’s Right Hand Rule.
Answer : (a) It is used to find the direction of magnetic field in a coil of wire and electric current in a straight conductor.
(b) It is used to find the direction of force exerted on a current carrying conductor in a magnetic field.
(c) It is used to find the direction of induced current in a closed circuit placed in a changing magnetic field, e.g. in an electric generator.

Question : (a) Mention the factors on which the direction of force experienced by a current carrying conductor placed in a magnetic field will depend.
(b) Under what conditions is the force experienced by a current carrying conductor placed in a magnetic field maximum?
(c) A proton beam is moving along the direction of a magnetic field. What force is acting on proton beam?
Answer : (a) (i) direction of current, (ii) direction of magnetic field.
(b) When direction of current is perpendicular to the direction of magnetic field, the force experienced will be maximum.
(c) No, force is exerted by a proton beam because proton beam is moving along the direction of magnetic field.

Question : How will the magnetic field produced at a point due to a current carrying circular coil change if we:
(i) increase the current flowing through the coil, (ii) reverse direction of current through coil,
(iii) increase the number of turns in the coil?
Answer : (i) The strength of magnetic field will increase. (B ∝ I)
(ii) The direction of magnetic field will be reversed.
(iii) The magnetic field produced will increase because magnetic field produced is directly proportional to the number of turns in the coil.

Question : Distinguish between a bar magnet and an electromagnet.
Answer : Bar Magnet
1. The bar magnet is a permanent magnet
2. It produces a comparatively weak magnetic force.
3. The strength of a bar magnet cannot be changed.
4. The polarity of a bar magnet is fixed and cannot be changed.
Electromagnet
1. An electromagnet is a temporary magnet.
2. It produces a very strong magnetic force.
3. The strength of an electromagnet can be changed by changing the number of turns in its coil or by changing the current passing through it.
4. The polarity of an electromagnet can be changed by changing the direction of current in its coil.

Question : Why and when does a current carrying conductor kept in magnetic field experiences force? List the factors on which direction of force will depend.
Answer : The movement of electrons takes place in the conductor in a particular direction when current is passed through it. These charged particles are moving in the magnetic field which experiences force.
The current carrying conductor has its own magnetic field, when it superimpose the magnetic field of magnet. Due to this, current carrying conducter experiences a force. Thus conductor experiences a
force when placed in a uniform magnetic field.
Factors on which direction of force depends:
(i) The direction of force depends upon the direction of magnetic field.
(ii) It also depends upon the direction of current flowing through the conductor

Question : What is meant of solenoid? How does a current carrying solenoid behave? Give its main use.
Answer : The long coil containing large number of close turns of insulated copper wires wrapped around, is called a solenoid.
Current carrying solenoid behaves like a bar magnet. It is called an electromagnet.
It is used for making electromagnets.