myclass24
myclass24your class. your pace.
Q&A BANK

every question.
answered.

1,535 answers across CBSE, ICSE, and State boards — Class 1 to 12, every subject.

CBSEICSEState
SUBJECT
CLASS

Filtered results

1,535 TOTAL
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

1.      Energy from various sources is considered to have been derived from the sun. Do you agree? Justify your answer.

Soln: Energy from various sources is considered to have been derived from the sun. Following points can justify the statement. Energy from fossils fuels are indirectly harnessed from sunlight because. Plants trap sunlight to produce food which ultimately makes biomass. Biomass gets converted to fossil fuels. Biomass will be helping in obtaining wood and gobar Water on the earth gets circulated because of kinetic energy possessed by Waves and ocean are formed due to heating of Hence sun is indirectly responsible for harnessing Tidal, Wave and Geothermal energy.

ScienceClass 10CBSE

1. What are the environmental consequences of using fossil fuels? Suggest the steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy.

Soln: Following are the consequences of using fossil fuels. Global warming will result due to increase in the level of Carbon-di-oxide, Sulphur oxides causes acid rain Burning of fossil fuels will result in accumulation of smog in big cities which will result in decreased visibility Air pollution leads to health hazrds to humans and Steps to minimise the pollution caused by various sources of energy including non-conventional sources of energy. Use of public transport Use of vehicles like electric bikes and bi-cycle that can reduce air pollution Adopting 3R’s policy- reduce, reuse and Afforestation

ScienceClass 10CBSE

1. Why is there a need for harnessing non-conventional sources of energy? How can energy be harnessed from the sea in different ways?

Soln: Following are the reason for the need to harness non-conventional sources of energy. Conventional sources are exhaustible source of energy and they will get exhausted in the near Non-conventional source of energy did not lead to environmental Energy can be harnessed from the sea in following ways Tidal energy: Tidal energy is harnessed by constructing a dam across a narrow opening to the sea. A turbine fixed at the opening of the dam converts tidal energy to electricity. As you can guess, the locations where such dams can be built are limited. Wave energy The kinetic energy possessed by huge waves near the seashore can be trapped in a similar manner to generate electricity. The waves are generated by strong winds blowing across the sea. Wave energy would be a viable proposition only where waves are very strong. Ocean Thermal Energy The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold. This difference in temperature is exploited to obtain energy in ocean-thermal-energy conversion plants.

ScienceClass 10CBSE

1.      Make a list of conventional and non-conventional sources of energy. Give a brief description of harnessing one nonconventional source of energy.

Soln: Conventional sources of energy are coal, petroleum, fire wood and tidal energy. Non-conventional sources are Solar energy, nuclear energy, Biogas, Tidal energy, Ocean thermal energy, wave energy etc. Methods to harness Non-conventional sources of energy. Solar Energy can be harnessed by using solar cookers, solar water heaters, solar cells and solar panels. Nuclear power can be converted to electric energy with the help of nuclear reactors. The water at the surface of the sea or ocean is heated by the Sun while the water in deeper sections is relatively cold. This difference in temperature is exploited to obtain energy in ocean-thermal-energy conversion plants. The kinetic energy possessed by huge waves near the seashore can be trapped in a similar manner to generate electricity. The waves are generated by strong winds blowing across the sea. Wave energy would be a viable proposition only where waves are very strong.

STILL STUCK?

Get a tutor for just your question.

One-on-one help, verified tutors. Matched within 24 hours.

Get Started →