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Why does a compass needle get deflected when brought near a bar magnet?

Why do not two magnetic lines of force intersect each other?

Consider a circular loop of wire lying in the plane of table. Let the current pass through the loop clockwise. Apply the right hand rule to find out the direction of the magnetic field inside and outside the loop.

The magnetic field in a given region is uniform. Draw a diagram to represent it.
 

Choose the correct option.
The magnetic field inside a long straight solenoid carrying current
1. is zero
2. decreases as we move towards its end
3. increases as we move towards its ends
4. is the same at all points.

Which of the following properties of a proton can change while it moves freely in a magnetic field.
1. mass
2. speed
3. velocity
4. momentum

A positively charged particle ($\mathrm{\alpha }$ particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
1. towards south
2. towards east
3. downward
4. upward

Explain different ways to induce current in a coil.

Name some sources of direct current.

Which sources produce Alternating Current (AC)?

Choose the correct option.
A rectangular coil of copper wire is rotated in a magnetic field. The direction of induced current changes once in each]
1. two revolutions
2. one revolutions
3. half revolution
4. one-fourth revolution

Name two safety measures commonly used in electric circuits and appliances.

An electric oven of 2 kW power rating is operated in a domestic circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.

An electric oven of 2 kW power rating is operated in a domestic circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.

What precautions should be taken to avoid the overloading of domestic electric circuits?

Which of the following correctly describes the magnetic field near a long straight wire?
1. The field consists of straight lines perpendicular to the wire
2. The field consists of straight lines parallel to the wire
3. The field consists of radial lines originating from the wire
4. The field consists of concentric circles centred on the wire

The phenomenon of electromagnetic induction is
'1. the process of charging a body
2. the process of generating magnetic field due to current passing through coil
3. the process of producing induced current in a coil due to relative motion between a magnet and the coil
4. the process of rotating a coil of an electric motor

The device used for producing electric current is called
1. generator
2. galvanometer
3. ammeter
4. motor

The essential difference between AC generator and DC generator is that
1. AC generator has electromagnet while DC generator has permanent magnet 
2. DC generator genrates higher voltage 
3. AC generator generates higher voltage
4. AC generator has slip rings while DC generator has commutator

At the time of short circuit, the current in the circuit
1. reduces substantially
2. does not change
3. increases heavily
4. vary continously

State whether the following statements are true or false.
1. An electric motor converts mechanical energy into electrical energy'
2. An electric generator works on the principle of electromagnetic induction
3. The field at the centre of a long circular coil carrying current will be parallel straight lines.
4. A wire with green insulation is usually the live wire of an electric supply.

List three methods of producing magnetic fields.
 

How does a solenoid behave like a magnet? Can you determine the North and South poles of a current carrying solenoid using a bar magnet? Explain.

When is the force experienced by a current carrying conductor placed in a magnetic field largest?

Imagine that you are sitting in a chamber with your back to one wall. An electron beam moving horizontally from back wall towards the front wall is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?

Name some devices in which electric motors are used?

A coil insulated of copper wire connected to a galvanometer. What will happen, if a bar magnet is
1. pushed into the coil,
2. withdrawn from inside the coil and 
3. held stationary inside the coil?

Two circular coils A and B are placed closed to each other. If the current in the coil A is charged?, will some current be induced in the coil B? Give reason.

Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?

When does an electric short circuit occur?

What is the function of an earth wire? Why it is necessary to earth metallic appliances?

What is meant by magnetic field?

How is the direction of magnetic field at a point determined?

Draw a diagram to show magnetic field due to a bar magnet in the given region.

Identify the poles of magnet in the figure.

What does the degree of closeness of magnetic field lines near the poles signify?

State the conclusion that can be drawn from the observation that a current carrying wire deflects a magnetic needle placed near it.

 constant current flows in a horizontal wire in the plane of the paper from East to West as shown in figure. At what point, the direction of magnetic field will be North to South?

The diagram given below represents magnetic field caused by a current carrying conductor. Identify the nature of the coil.

Identify the region, where the magnetic field around a current carrying solenoid is uniform.

State the direction of magnetic field in the following case.

Name the rule which gives the direction of induced current in a conductor.

Under what orientation the induced current produced in moving conductor in a magnetic field can be maximum?

How is induced current in a secondary coil related to current in a primary coil?

Why is an alternating current considered to be advantageous over direct current for long range transmisson of electric energy?

An alternating current has frequencing of 50 Hz. How many times does it change its direction in one second?

How is the type of current that we receive in domestic circuit different from one that runs a clock?

In a domestic electric circuit, mention the potential difference between live wire and neutral wire and frequency of AC?

How should the electric lamps in a building be connected, so that the switching on or off in a room has no effect on other lamps in the same building?

What is the advantage of third wire of the earth connection in domestic electrical application?

Which is the most important safety method used for protecting home appliances from short circuiting or overloading?

A region A has magnetic field lines relatively closer than another region B. Which region has stonger magnetic field? Give reason to support your answer.

What does the divergence of magnetic field lines near the ends of a current carrying straight solenoid indicate?

A horizontal power lines carries a current from East to West direction. What is the direction of the magneticfield due to the current in the power line at a point above and at a point below the power line?

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 
1. $\mathrm{\alpha }$-particles
2. neutrons? Justify your answer

How does the strength of magnetic field due to a current carrying conductor depend upon
1. distance from the conductor?
2. current flowing through the conductor?

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? Suupport your answer with a reason.

State what would happen to the direction of rotation of a motor, if
1. the current were reversed?
2. both current and magnetic field were reversed simultaneously?

Name four appliances where in 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?

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?

1. 
The diagram shows a bar magnet surrounded by four plotting compasses. Copy the diagram and mark the direction of the compass needle for each of the cases B, C and D.
2. Which of the North pole, X or Y?

A plotting compass is placed inside a solenoid and the compass needle is pointing in the direction as shown.

1. Complete the diagram by drawing arrow heads to indicate the direction of the current flow.
2. Describe the direction of the magnetic field inside the solenoid.

The wire in the figure below is being moved towards through the magnetic field, so as to produce induced current.

What would be the effect of
1. moving the wire at a higher speed?
2. moving the wire upwards rether than downwards?
3. using a stronger magnet?
4. holding the wire still in the magnetic field?

The given figure shows a DC motor model used by a student to study electromagnetism.

The two ends of the coil are fixed to a pair of curve elastic metal strips. The matal strips are connected to the power supply with a rheostat.
1. State the direction of rotation of the coil when viewed from the front.
2. The student is still testing on the feasibility of using the metal strips in the model. What is he trying to achieve?

The figure shows the split ring commutator and the two carbon brushes in their respective positions. 

What can you say about carbon brush and split ring commutator?

What are the magnetic field lines? Justify the following statements.
1. Two magnetic field lines never intersect each other.
2. Magnetic field lines are closed curves.

State the purpose for which the following rules are used
1. Right-hand thumb rule
2. Fleming's left-hand rule
3. Fleming's right-hand rule

Describe an activity with a diagram to demonstrate the presence of a magnetic field around a current-carrying straight conductor.

The flow of current in a circular wire creates a magnetic field be detected? State the rule which helps to predict the direction of magnetic field.

Meena draws magnetic field lines of field close to the circular loop she observes that the lines keep on diverging. How will you explain her observation?

Find the direction of magnetic field due to a current carrying circular coil held:
1. vertically in North-South plane and an observer looking it from East sees the current to flow in anti-clockwise direction.
2. verticalli in east-west plane and an observer looking it from south sees the current to flow in anti-clockwise direction.
3. Horizontally and an observer looking at it from below sees current to flow in clockwise direction.

The diagram shows the lengthwise section of a current-carrying solenoid.
$\otimes$ Indicates current entering into the page
$\odot$ indicates current emerging out of the page.

Decide which end of the solenoid A or B, will behave as the North Pole. Give a reason for your answer. Also, draw field lines inside the solenoid.

For the current-carrying solenoid as shown below draw magnetic field lines and give reason to explain that out of the three points A, B, and C at which point the field strength is maximum and at which point it is minimum.

A circular metallic loop is kept above the wire AB as shown below:

What is the direction of induced current produced in the loop, if any when the current flowing in the straight wire
1. is steady, i.e. does not vary?
2. is increasing in magnitude?
Justify your answer in each case.

A copper coil is connected to a galvanometer. What would happen, if a bar magnet is
1. pushes into the coil with it's north pole entering first?
2. held at rest inside the coil?
3. pulled out again?

Under what condition permanent electromagnet is obtained, if a current-carrying solenoid is used? Support your answer with the help of a labeled circuit diagram.

A magnetic compass needle is placed in the plane of paper near point A as shown in figure. 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?

1. Two circular coils P and Q are kept close to each other, of which coil P carries a current. If coil P os moved towards Q, then will some current be induced in coil Q? Give a reason for your answer and name the phenomenon involved.
2. What happens, if coil P is moved away from Q?
3. State few methods of inducing current in a coil.

What is an electric fuse? what is its role in electric circuits? Should it be placed on neutral wire or on live wire? Justify your answer.

1. Describe an activity to obtain a magnetic field line around the current-carrying straight conductor.
2. State the rule used to find the direction of this magnetic field.
3. How does the magnitude of the magnetic field depend on the current through a conductor?

1. Draw the magnetic field lines through and around a single loop of wire carrying electric current.
2. State whether an $\mathrm{\alpha }$-particle will experience any force in a magnetic field, if ($\mathrm{\alpha }$-particles are positively charged particles).
a. It is placed in the field at rest.
b. It moves in the magnetic field parallel to field lines
c. It moves in the magnetic field perpendicular to field lines.
Justify your answer in each case.

Explain the meaning of words "electromagnetic" and "induction" in the term electromagnetic induction. List three factors on which the vale of induced current produced in a circuit depends.
Name and state the rule used to determine the direction of the induced current. State one practical application of this phenomenon in everyday life.

Draw a labeled circuit diagram of a simple electric motor and explain its working. In what way these simple electric motors are a different form of commercial motors?

1. What is meant by electromagnetic induction? Name one device which works on the electromagnetic induction.
2. Describe three different ways to produce induced current in a coil of wire.

Differentiate between AC and DC. Name one source of each. Write any two advantages of alternating current over direct current.

Explain why electric power transmitted at high voltages and low currents to distant places?

Describe the working of an AC generator with the help of a labeled circuit diagram. What changes must be made in the arrangement to convert it into a DC generator?

Shikhaj's younger brother was playing with a magnet. Shikhaj advised him not to play with the magnet but his brother brought the magnet near the screen of the television that shikhaj was watching.
His TV got a permanent dark patch on the area where magnet was brought near the screen. His TV screen was partially damaged. Shikhaj immediately informed all his friends to be aware of such episodes at home.
Read the above passage and answer the following questions:
1. Why did TV get dark patch when was brought closer?
2. Name two devices used at home which has electromagnetic effect in them.
3. What values of Shikhaj is seen in the above case?

A boy was making a model of electric bell. He connected the coil in the circuit and switched it on. However, the magnetism produced in the coil was not strong enough. Then, he made some changes in the coil and the circuit was now working properly. He also found out other ways of producing a strong magnetism 
Read the above passage and answer the following questions:
1. What changes did the boy make in the coil?
2. What values of the boy would you appreciate?
3. Which other ways did he discover for increasing the strength of magnet?

Mahesh bought an electric iron and connected its wires into the two-pin plug. Obviously, the green wire was not connected anywhere. A few days later his wife got a severe electric shock while ironing the clothes. The electrician told Mahesh that this situation could be averted, if he had connected the green wire also, using the three-pin plug. Mahesh learned a lesson for a lifetime.
Read the above passage and the answer the following questions:
1. Which terminal was to be connected using green wire?
2. What qualities does Mahesh need to incorporate in himself to avoid such mistakes?
3. If you were the electrician, what else would you do than explaining to Mahesh?
 

One day Neil connected many household high power appliances having a current rating more than 6 A to a multiple of 6 A rating. When he was about to switch them on, his older sister shouted and asked him to remove the appliances from a single socket.
Read the above passage and answer the following questions:
1. According to you, why she would not advice to connect multi-high power appliances on a single socket?
2. What would have happened, if he switched them on?
3. What was the value shown by Neil's sister?

1. define the following terms in the context of spherical mirrors:
a. Pole 
b. Centre of curvature
c. Principal axis
d. Principal focus
2. draw ray diagrams to show the principal focus of a:
a. concave mirror
b. convex mirror