Magnetic Effects of Electric Current: Class 10 Science Q&A
51 free answers on Magnetic Effects of Electric Current (Science) for Class 10 students, across CBSE, ICSE and State boards. Includes questions such as “What is the role of the two conducting stationary brushes in a simple electric motor?”, “What is the function of an earth wire? Why is it necessary to earth metallic appliances?”
Question & Answer
Questions
- ScienceClass 10CBSE
1. Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current carrying loop is brought near it. Describe some salient features of magnetic lines of field concept.
Current carrying loops acts as bar magnets which have associated lines of field. This changes existing earth’s magnetic field and a deflection results. Magnetic field has both direction and magnitude. Magnetic field lines emerge from north pole and enter south pole. The magnetic field strength is represented diagrammatically by the degree of closeness of the field lines. Two values of net field cannot exist as a single point as field lines cannot cross each other. Only one value, a uniq
- ScienceClass 10CBSE
1. What is the role of fuse, used in series with any electrical appliance? Why should a fuse with defined rating not be replaced by one with a larger rating?
Fuse has have thin wire of short length made of tin and lead in the ratio of 75: 25%. When current exceeds specified limit fuse melts and breaks the circuits thereby protecting home appliances. If a fuse is replaced by one with larger ratings, the appliances may get damaged while the protecting fuse does not burn off. This practice of using fuse of improper rating should always be avoided.
- ScienceClass 10CBSE
1. What is the difference between a direct current and an alternating current? How many times does AC used in India change direction in one second?
In AC current direction of current will be changing constantly where as in DC current direction remains unaltered. In India AC Changes direction 100 times in a second.
- ScienceClass 10CBSE
1. What is the role of the two conducting stationary brushes in a simple electric motor?
The two conducting stationary brushes draw current from the battery and supply it to the armature of the motor as they touch the outer sides of the two halves of the split rings, The inner sides of split rings are Insulated and attached to the axle of the motor.
- ScienceClass 10CBSE
1. Name four appliances wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. In what respect motors are different from generators?
Electric fans, mixers, washing machines, computer drives, are the examples wherein an electric motor, a rotating device that converts electrical energy to mechanical energy, is used as an important component. Motors convert electrical energy into mechanical energy whereas generators convert mechanical energy into electrical energy.
- ScienceClass 10CBSE
1. What does the divergence of magnetic field lines near the ends of a current carrying straight solenoid indicate?
The divergence of magnetic field lines near the ends of a current carrying straight solenoid indicates fall in strength of magnetic field near and beyond the ends of the solenoid.
- ScienceClass 10CBSE
1. Meena draws magnetic field lines of field close to the axis of a current carrying circular loop. As she moves away from the centre of the circular loop she observes that the lines keep on diverging. How will you explain her observation.
With decrease in the distance strength of magnetic field decreases. Decrease in degree of closeness of the lines of field indicates it.
- ScienceClass 10CBSE
1. What does the direction of thumb indicate in the right-hand thumb rule. In what way this rule is different from Fleming’s left-hand rule?
Thumb held by curled fingers indicates the direction of current in right hand rule whereas in fleming’s left hand rule force experienced by current carrying conductor placed in an external magnetic field.
- ScienceClass 10CBSE
1. It is established that an electric current through a metallic conductor produces a magnetic field around it. Is there a similar magnetic field produced around a thin beam of moving (i) alpha particles, (ii) neutrons? Justify your answer.
alpha particles constitutes current in the direction of motion as they are positively charged constitutes . Neutron has no charge on them hence they do not conduct
- ScienceClass 10CBSE
1. A magnetic compass shows a deflection when placed near a current carrying wire. How will the deflection of the compass get affected if the current in the wire is increased? Support your answer with a reason.
As the deflection increases. The strength of magnetic field will be directly proportional to the magnitude of current passing through the straight conductor.
- ScienceClass 10CBSE
A magnetic compass needle is placed in the plane of paper near point A as shown in Figure 13.6. In which plane should a straight current carrying conductor be placed so that it passes through A and there is no change in the deflection of the compass? Under what condition is the deflection maximum and why?
In the plane of the paper itself. The axis of the compass is vertical and the field due to the conductor is also vertical. It could result in a dip of compass needle which is not possible in this case (dips result only if axis of compass is horizontal). The deflection is maximum when the conductor through A is perpendicular to the plane of paper and the field due to it is maximum in the plane of the paper.
- ScienceClass 10CBSE
1. The most important safety method used for protecting home appliances from short circuiting or overloading is (a) earthing (b) use of fuse (c) use of stabilizers use of electric meter
Soln: Answer is (b) use of fuse Explanation: Fuse has have thin wire of short length made of tin and lead in the ratio of 75: 25%. When current exceeds specified limit fuse melts and breaks the circuits thereby protecting home appliances.
- ScienceClass 10CBSE
1. To convert an AC generator into DC generator (a) split-ring type commutator must be used (b) slip rings and brushes must be used (c) a stronger magnetic field has to be used a rectangular wire loop has to be used
Soln: Answer is (a) split-ring type commutator must be used Explanation: Split-ring type commutator reverse the direction of current after each half turn of armature. This maintains a DC current.
- ScienceClass 10CBSE
1. The strength of magnetic field inside a long current carrying straight solenoid is (a) more at the ends than at the centre (b) minimum in the middle (c) same at all points found to increase from one end to the other
Soln: Answer is (c) same at all points Explanation: Inside the solenoid magnetic field lines are straight. This indicates strong magnetic field. Hence magnetic field is uniform at all points inside the solenoid.
- ScienceClass 10CBSE
1. Choose the incorrect statement (a) Fleming’s right-hand rule is a simple rule to know the direction of induced current (b) The right-hand thumb rule is used to find the direction of magnetic fields due to current carrying conductors (c) The difference between the direct and alternating currents is that the direct current always flows in one direction, whereas the alternating current reverses its direction periodically (d) In India, the AC changes direction after every 1/50 second
Answer is (d) In India, the AC changes direction after every 1/50 second Explanation: AC frequency in India is 50 Hz. The direction changes twice in each cycle so that change of direction takes place after every 1/00 second.
- ScienceClass 10CBSE
1. 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 (a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid (b) The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil (c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet The N- and S-poles exchange position when the direction of current through the solenoid is reversed
Soln: Answer is (c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet Explanation: Solenoid behaves like Bar magnet, therefore the pattern of the magnetic field associated with the solenoid is same as the pattern of the magnetic bar around a bar magnet.
- ScienceClass 10CBSE
1. Choose the incorrect statement from the following regarding magnetic lines of field (a) The direction of magnetic field at a point is taken to be the direction in which the north pole of a magnetic compass needle points (b) Magnetic field lines are closed curves (c) If magnetic field lines are parallel and equidistant, they represent zero field strength Relative strength of magnetic field is shown by the degree of closeness of the field lines
Answer is (c) If magnetic field lines are parallel and equidistant, they represent zero field strength Explanation: Option c) is incorrect because parallel lines of magnetic field represent uniform magnetic field.
- ScienceClass 10CBSE
What is the function of an earth wire? Why is it necessary to earth metallic appliances?
Solution: The metallic body of electric appliances is earthed by means of an earth wire. Any leakage of electric wire is transferred to the ground by means of the earth wire. This prevents the user of the electric appliance from getting electric shocks. This is the reason why it is important for metallic appliances to be earthed.
- ScienceClass 10CBSE
Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
Solution: The electric generator converts mechanical energy into electrical energy. The working principle of the electric generator is electromagnetic induction. It generates electricity by rotating a coil in the magnetic field. The figure below shows the construction of a simple AC generator. In the diagram, A and B are brushes. C and D are slip rings. X is the axle. G is the galvanometer. When the axle X is rotated clockwise, MN moves
- ScienceClass 10CBSE
State the rule to determine the direction of a (i) magnetic field produced around a straight conductor-carrying current, (ii) force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it, and (iii) current induced in a coil due to its rotation in a magnetic field.
(i) The rule used to determine the direction of the magnetic field produced around a straight conductor-carrying current is Maxwell’s right-hand thumb rule. (ii) The rule used to determine the force experienced by a current-carrying straight conductor placed in a magnetic field which is perpendicular to it is the Fleming’s left hand rule. (iii) The rule used to determine the current induced in a coil due to its rotation in a magnetic field is Fleming’s right-