NIOS Class 10 Science Worksheet 17 Questions Answers – Magnetic Effects of Electric Current

This worksheet 17 contains questions based on Chapter 17 Magnetic Effects of Electric Current with complete answers.

This post explains the answers of questions given in the worksheet including explanation, diagrams. These solutions will help you complete your assignments and TMA also.

Magnetic Effects of Electric Current Worksheet 17 Solution

This chapter explains magnets and their properties, concept of magnetic field, magnetic force lines, magnetic effect of electric current. This worksheet has been explained on the basis of this chapter.

Q1. Perform an activity to prove that if a magnet is suspended freely with the help of a string, it always rests in the north-south direction. Observe and comment what happens if the magnet is slightly turned from this direction.

 

Answer

Activity: To show that a magnet always rest in the north-south direction when suspended freely.

Aim

To prove that a magnet when suspended freely always comes to rest in the north-south direction

Materials Required

    1. Bar magnet

    2. Thin thread

    3. Stand or hook

Procedure

   1. Tie a thin thread at the middle of a bar magnet

    2. Suspended the magnet freely from a stand or hook.

    3. Allow the magnet to come to rest.

   4. Now note the direction in which the magnet settles.

Observation

The suspended magnet always comes to rest in the north-south direction. When we turned the magnet slightly, it oscillates and again settles in the north-south direction.

Explanation & conclusion

A freely suspended magnet aligns itself in the north-south direction due to the Earth’s magnetic field. This also proves that the Earth behaves like a giant magnet.

 

 

Q2. Continue to Q1, explain why a magnet rests in the north-south direction if it is suspended freely.

Answer

A magnet rests in the north-south direction when suspended freely because of the Earth’s magnetic field. The earth behaves like a magnet and it has north and south poles.

When a magnet is suspended freely, its north pole points towards the earth’s south pole and its south pole toward the earth’s magnetic north pole.

 

 

Q3. Take one magnetic needle, two bar magnets, some iron filling and perform different activities to verify the properties of magnet. On the basis of observation; list properties of magnet.

Answer

Aim

To study the properties of a bar magnet such as direction of rest, attraction and repulsion, magnetisation etc.

Materials Required

    1. Bar magnets (two)

    2. Magnetic needle

    3. Iron filings

    4. Iron Alpin

    5. String and hook

Procedure

1.  We tie a string at the middle of a bar magnet and hang it with the help of a hook and notice what happens?

2. Now we take iron filings near the bar magnet and observe what happens to them?

3. After that we bring one pole of bar magnet near the pole of suspended bar magnet and observe.

4. Now we place an Alpin near the bar magnet and notice the change in the Alpin.

5. We break the bar magnet into smaller pieces and test each piece for magnetic properties.

Observation

    1. The bar magnet always rests in the north- south direction.

   2. Iron filings stick to the magnet. The density of filings is more near the poles of magnet.

   3. We can see like poles repel each other but unlike poles attract each other.

   4. The Alpin becomes a magnet and attracts iron filings.

   5. Each piece of the broken bar magnet behaves like a complete magnet and have same properties as the original bar magnet has.

Explanation

A freely suspended bar magnet always aligns itself along the Earth’s magnetic field pointing north-south. The magnetic field is strongest at the poles so iron filings gather there. Like poles repel each other and unlike poles attract each other; this is fundamental property of magnet.

When a magnetic material is placed near a magnet for some time, it acquires magnetism by magnetic induction. Each broken part of a magnet acts as a separate magnet with north and south poles.

Conclusion

We can conclude that:

    1.  A magnet always points in the north-south direction when suspended freely.

    2. Magnetic force is strongest at the poles.

    3. There is attraction between unlike poles and repulsion between like poles of a magnet.

    4. Magnetism can be induced in iron materials.

    5. Each broken piece of a large magnet acts as a small magnet with the same properties.

 

Q4. Take one magnetic needle and one bar magnet. Keep magnetic needle near the bar magnet. You will observe that the magnetic needle rotates and stops in a particular direction only. The direction of magnetic needle changes continuously and it takes the curved path while moving from north to south. Explain the phenomenon why the needle stops at a specific direction. Does magnetic field exist throughout space?

Answer

 

When a magnetic needle is kept near a bar magnet, the needle starts rotating because it experiences a magnetic force due to the magnetic field of bar magnet.

The needle follows a curved path from the north pole to the south pole of the bar magnet. This curved path represents the magnetic lines of force.

The magnetic needle stops at a specific direction because it aligns itself along the direction of the magnetic field at that point. When the needle becomes parallel to the magnetic field lines, the torque acting on it becomes zero and the needle stops rotating.

Yes, a magnetic field exist throughout space but its strength decreases with distance from the magnet.

 

 

Q5. Continue to Q4, using magnetic needle and bar magnet; draw magnetic line of forces. On the basis of observation; list properties of magnetic line of forces.

Answer

 

1. Magnetic lines of force start from the north pole and end at the south pole of a magnet.

2. They are closed and continuous curves.

3. Two magnetic lines of force do not intersect each other.

4. Magnetic lines of force are close near the poles.

5. The direction of the magnetic field at any point is given by the direction in which the magnetic needle points.

 

 

Q6. Perform an activity to prove that if an electric current is made to flow in a wire, magnetic field is produced around it. Observe your surroundings and write one application of the principle of the magnetic effect of electric current.

Answer

Aim

To prove that a magnetic field is produced due to electric current

Materials Required

    1. Straight copper wire

    2. Battery

    3. Connecting wires

   4. Switch

   5. Magnetic needle

Procedure

We connect copper wire, battery, switch with connecting wires and make a simple circuit. Now we place a magnetic needle near the straight copper wire and note the position of the magnetic needle.

 Now we close the switch so that electric current flow in the wire. Again we notice the position of needle.

Now we reverse the terminals of the battery and again observe the needle.

Observation

   1. When no current flows in the circuit, the magnetic needle stays in the north-south direction.

   2. When current flow through the wire, the needle gets deflected.

   3. When the direction of current reversed, the direction of deflection of needle also reverses.

Conclusion

 This experiment proves that electric current produces a magnetic field around a current carrying conductor. The direction of magnetic field depends on the direction of current.

 

Application of the principle of the magnetic effect of electric current.

 

An electric motor works on the principle of the magnetic effect of electric current. Electric motor is used in fans, mixers, washing machines etc.

 

 

Q7. Define electromagnet. Make an electromagnet using thick paper like drawing sheet, copper wire, 9 V battery or eliminator through which milli ampere current may flow, switch and iron scale.

Aim

Making  of an electromagnet

Materials Required

   1.  Thick paper or drawing sheet

    2. Insulated copper wire

   3. 9 V battery

   4. Switch

   5. Iron scale

   6. Iron nails

Procedure

We take a thick paper and make a cylindrical tube about 15 cm and 1 cm in diameter. Then we wind around 100 to 150 turns of insulated copper wire around this paper tube.

Now we connect the ends of wire to a 9-volt battery through a switch.

We bring an iron scale close to the tube before switching on the current and notice what happens. Now we turn the switch on to flow current in the tube and notice what happens between iron scale and the tube.

We fill the tube with small iron nails and observe what happens.

Observation

   1. When the electric current is off, there is no attraction between tube and iron scale.

   2. When the current is on, the tube attracts the iron scale just like a magnet.

   3. The magnetic effect increases when iron nails are placed in the tube.

   4. When current is stopped in the tube, the magnetic effect disappears.

Explanation

When electric current is passed through the coiled insulated wire around the paper tube, a magnetic field is produced around it. This magnetic field make the tube like a bar magnet which is called electromagnet.

When iron core is inserted in the tube, the magnetic strength increases.

When electric current is stopped, the magnetic field also disappears.

Conclusion

We can conclude that electric current produce magnetic effect. This activity also prove that electricity and magnetism are related to each other.

 

Q8. Continue to Q7, we have seen that magnetic field created when current flows through a solenoid. Do you think that the reverse should also be possible which means conversion of electricity from magnetism?

Answer

Yes, electricity can be produced from magnetism and the phenomenon is called electromagnetic induction.

When there is a change in magnetic field around a conductor or solenoid.

Electric current is created by

i.        Moving a magnet towards or away from the coil.

ii.    Rotating a coil in a magnetic field.

 

The magnetic lines of force associated with the coil change continuously so electric current is produced in the coil. This phenomenon is known as electromagnetic induction.

 

Q9. Observe your surroundings; you will see     electricity poles, transformers, wires etc. around your houses. The production of electricity is done far away from cities at electricity generation centres. Write the system and process by which electricity is transmitted from such centres to the consumers.

Answer

Electricity is generated at electricity generation centres which are located far away from cities. The system by which electricity reaches our homes has main two parts

(i)         Transmission system

(ii)    Distribution systematic

(i)   Transmission system: -

 a). Electricity is produced at about 11kV and 50Hz at electricity generation centres.

 b). This voltage is increased to high voltage (132 kV) using step up transformers.

c). This increase in voltage reduces the current and minimize energy loss during long distance transmission.

d). The high voltage electricity is carried to substations through high tension lines.

(ii)    Distribution system

a). The high voltage electricity is reduced to 3.3kV using step down transformers at substations.

b). Now electricity is sent to local distribution points.

c). This electric current is reduced to 220 V by using another step-down transformer.

d). Electricity reaches homes through distribution poles and wires

Supply to houses

Two wires carry the electricity to houses –(i) Phase wire (ii) Neutral wire

An earth wire is also provided for safety purpose. Household appliances are connected in parallel

 

Q10. If electricity is used with careful and safe measures, it is the largest and most convenient form of energy. If one uses it carelessly it will become lethal.

    a.  Observe and list the precautions to be taken while using electrical energy.

    b. Observe and list the accidents caused by electricity.

    c.  Observe and list the safety devices used in electrical circuit to avoid accidents caused by electricity.

    Answer

Electricity is very useful in our daily life and perform various task through appliances. But we should be careful while using electricity.

Precautions to be taken while using electrical energy

i.      Always switch off the main supply before repairing any electrical circuit.

ii.   Never touch electrical wires or appliances with wet hands.

iii.  Do not touch bare or damaged wires.

iv.  Wear rubber gloves and rubber soles shoes while working with electricity.

v.     Ensure proper earthing of all electrical appliances.

vi.  Avoid overloading

Accidents caused by electricity

i.     Leakage o current due to damaged insulation of wires.

ii.  Short circuit when live and neutral wires come into contact.

iii.  Overloading of electrical circuits by using too many appliances at same time.

iv.    Electric shock due to improper earthing.

v.  Fire accidents caused by spark, short circuit or overloading of wires.

Safety devices used in electrical circuit to avoid accidents

i.   Electrical fuse: - It is made of a metal alloy with low melting point and high resistance.

ii.    Miniature Circuit Breaker (MCB): - This device automatic cuts off the supply during overloading or short circuit.

iii. Earthing: - This wire provides an alternative low resistance path for leakage current and protect from electric shock.

iv.  Main switch: - This switch allows complete disconnection of electricity during emergencies.