Solution of Chapter 13. Magnetic Effects of Electric Current (Xam idea - Science Book)

State the rule which gives the direction of force acting on a current-carrying conductor kept in a magnetic field.

What does the degree of closeness of the field lines represent?

What is the safety method used for protecting home appliances short circuiting or overloading in domestic electric fittings?

A charged particle enters at right angles into a uniform magnetic field as shown. What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to its interaction with the magnetic field?

Why cannot two magnetic field lines cross each other?

Name the phenomenon which is made use of in an electric generator.

What change should be made in an AC generator so that it may become a DC generator?

Why it necessary to connect an earth wire to electric appliances having metallic bodies?

A student while studying the force experienced by a current-carrying conductor kept in a magnetic field records the following observations:

i. The force experienced by the conductor increases as the current is increased.

ii. The force experienced by the conductor decreases as the strength of the magnetic field is increased.

Which of the two observations is correct and why?

Copy and complete the diagrams to show the shape and direction of the magnetic field between the magnetic poles.

Why are the magnetic field lines close curves?

If instead of electron a neutron enters a field, what will be its direction of motion? Give reasons for your answer.

What is the principle of an electric generator?

Two fuse wires of same length are rated 5 A and 20 A. Which of the two fuse wires is thicker and why?

a. On what principle does an electric fuse work?

b. What is the frequency of A.C. in India? State one advantage of A.C over D.C.

Two coils 1 and 2 of insulated copper wire having large but different number of turns are wound over a cardboard cylinder. Coil 1 is connected to battery and a plug key. Coil 2 is connected to a galvanometer.
How will the galvanometer reading change when

(i) key is plugged in and

(ii) key is taken out? Give reason for your answer in each case.

Under what conditions permanent electromagnet is obtained if a current carrying solenoid is used? Support your answer with the help of a labelled circuit diagram.

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

How will the magnetic field produced at a point P by a current carrying-circular coil change if we increase the

i. value of current flowing through the coil,

ii. distance of the point P from the coil,

iii. number of turns of the coil?

Shown in the given diagrams (a), (b) and (c) are the magnetic fields around different systems. Identify them. Compare the pattern of the field lines in all the three systems.

Explain why the direction of the induced current in the coil of an AC generator changes after every half revolution of the coil.

A student fixes a sheet of white paper on a drawing board. He places a bar magnet in the centre of it. He sprinkles some iron filings uniformly around the bar magnet. Then he taps the board gently and observes that the iron filings arrange themselves in a particular pattern.

a. Why do the iron filings arrange in a pattern?

b. What does the crowding of iron filings at the end of the magnet indicate?

c. What does the lines along which the iron filings align represent?

d. Draw a neat diagram to show the magnetic field lines around a bar magnet.

e. Write any two properties of magnetic field lines.

a. A stationary charge is place in a magnetic field. Will it experience a force? Give reason to justify your answer.

b. On what factors does the direction of force experienced by a conductor when placed in a magnetic field depend?

c. Under what conditions is the force experienced by a current carrying conductor placed in a uniform magnetic field maximum?

d. under what conditions is the force experienced by a current carrying conductor placed in a uniform magnetic field maximum?

Two coils C₁ and C₂ are wrapped around a non conducting cylinder. Coil C₁ is connected to a battery and key and C₂ with galvanometer G. On pressing the key (K), current starts flowing in the coil C₁. State your observation in the galvanometer:

i. When key K is pressed on.

ii. When current in the coil C₁ is switched off.

iii. When the current is passed continuously through coil C.

iv. Name and state the phenomenon responsible for the above observation. Write the name of the rule that is used to determine the direction of current produced in the phenomena.