CBSE Class 10 Science Magnetic Effects Of Current Worksheet Set A

Assertion and Reasoning Based Questions :

Question. Assertion: A current carrying conductor experiences a force in a magnetic field.
Reason: The net charge on a current carrying conductor is zero.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false, but reason is true.

Answer: B

Question. Assertion: Magnetic field lines do not intersect each other.
Reason: There are two direction of the magnetic field at a point.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false, but reason is true.

Answer: A

Question. Assertion: The energy of charged particle moving in a uniform magnetic field does not change.
Reason: Work done by magnetic field on the charge is zero.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false, but reason is true.

Answer: A

Question. Assertion: The principle of electromagnetic induction was discovered by Micheal Faraday
Reason: The principle is used only in DC generators
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false, but reason is true.

Answer: C

Question. Assertion: A pump operated by electric motor starts pumping liquid.
Reason: Motor converts mechanical energy to electrical energy.
(a) If both assertion and reason are true and reason is the correct explanation of assertion.
(b) If both assertion and reason are true, but reason is not the correct explanation of assertion.
(c) If assertion is true, but reason is false.
(d) If assertion is false, but reason is true.

Answer: C 

Question. Name the type of current: (a) used in household supply (b) given by a cell.
Answer :  a. We use alternating current in our houses which changes to direction and magnitude with time.
b. A cell supply direct current (DC) or unidirectional current which flows only in one direction only.

Question. Suggest one way of discriminating a wire carrying current from a wire carrying no current.
Answer :  When a magnetic compass is brought near a current carrying conductor it will be deflected. If magnetic compass remains undeflected near a conductor then there is no current in it.

Question. Write any one method to induce current in a coil.
Answer :  By moving a magnet towards the coil or vice versa, current can be induced in the coil.

Question. State the rule which you use to find the direction of induced current or state Fleming’s right hand rule.
Answer :  Fleming’s right hand rule gives the direction of current produced in a conductor. According to Fleming’s right hand rule, if we stretch right hand thumb, forefinger and middle finger perpendicular to each other in such a way that thumb points the direction of force on a conductor and forefinger points the direction of magnetic field then middle finger will point the direction of current produced in the conductor.

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

Answer :  Perpendicular to both current and force on the conductor outward the plane of paper.

Question. Why are magnetic field lines closed curves?
Answer :  By convention the magnetic field lines are the path traced by north pole which emerges from north pole and goes to the south pole and inside the magnet the direction of field lines are from south pole to north pole, forming continuous closed path.

Question. How can it be shown that a magnetic field exists around a wire through which a direct current is passing.
Answer :  When we put a small magnetic compass near a current carrying conductor it gets deflected, which shows that a magnetic field is produced near a current carrying conductor.

Question. What type of core is used to make an electromagnet?
Ans : Soft iron core is used in making an electromagnet.

Question. What will be the frequency of an alternating current if its direction changes after every 0.01 s?
Answer :  The direction of ac changes every 0.01 sec. 
Thus time of one complete cycle = 0.02 sec
  i.e. in 0.02 sec no. of cycle = 1
            in 1 sec no. of cycle = 1/0.02 = 100/2 = 50
                  Frequency of ac = 50 Hz

Question. Mention the special feature regarding shape of magnetic field lines.
Answer :  Magnetic field lines are continuous closed loops.

Question. What constitutes the field of a magnet?
Answer :  The magnetic field is created by the magnet or when a charge particle is moving with some velocity in both cases they produce a magnetic field around them. The magnetic field is due to current or magnetic material.

Question. How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire?
Answer :  The magnetic field strength at a point near a wire is directly proportional to the current strength in the conductor.

Question. State the direction of the magnetic field inside the bar magnet.
Answer :  In a magnet, magnetic field lines goes from S pole to N pole.

Question. Mention the voltage and frequency of current that we receive at our house.
Answer :  In our house we get AC of voltage 220 V and frequency 50 Hz.

Question. What does the thumb indicated in Fleming’s right hand rule?
Answer :  Thumb indicate the direction of force on conductor i.e. motion of the conductor.

Question. If field lines of a magnetic field are crossed at a point, what does it indicate?
Answer :  If the magnetic field lines would cross each other then at the same point there would be two directions of magnetic field which is not possible.

Question. Draw a diagram to represent a uniform magnetic field in a given region.
Answer :  Uniform magnetic field is represented by equidistant parallel lines.

Question. When is the force experienced by a current carrying conductor placed in a magnetic field the maximum?
Answer :  A current carrying conductor experience maximum force in a magnetic field when the direction of current is perpendicular to the magnetic field.

Question. An alternating electric current has a frequency of 50 Hz. How many times does it change its direction in one second?
Answer :  50 Hz ac changes its direction 100 times in 1 sec.

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 decreases?
Answer :  If we bring a magnetic compass from a distance to near a current carrying conductor its deflection goes on increasing and when magnetic compass is brought away from the current carrying wire its deflection goes on decreasing which shows that magnetic field near current carrying wire is maximum and decreasing on increasing the separation.

Question. Mention the shape of the magnetic field lines around a current carrying straight conductor.
Answer :  The magnetic field lines around a current carrying straight conductor are in the form of concentric circular rings around a conductor.

Question. What is the pattern of field fines inside a solenoid? What do they indicate?
Answer :  The magnetic field inside a solenoid is uniform in the form of parallel lines.

Question. How is the magnetic field produced in a solenoid used?
Answer :  Magnetic field produced in a solenoid can be used in making a soft iron piece electromagnet.

Question. What is short-circuiting in an electric supply?
Answer :  When a neutral wire and live wire come in contact with each other short circuit takes place.

Question. What does the direction of thumb indicate in the right-hand thumb rule?
Answer :  Thumb points the direction of current in the conductor holding a straight conductor in right hand.

Question. State the observation made by Oersted on the basis of his experiment with current carrying conductors.
Answer :  A magnetic field is produced near a current carrying conductor which last so long till there is current in the conductor on reversing the current the direction of magnetic field is also reversed.

Question. How is the induced current in a secondary coil related to current in a primary coil?
Ans : Induced current in a secondary coil may be more or lesser than the current in primary coil depending upon the number of turns in secondary.

Question. What is the advantage of the third wire of earth connection in domestic appliances?
Answer :  In case of any electric fault in domestic appliances, current may comes in appliance body. The third wire called earth wire transfer this current to the earth and user remains safe from any such electric shock.

Question. 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?
Answer :  If the angle between a current carrying conductor and magnetic field is 90° then the force experienced by the conductor is maximum.