# Magnetic Effect of Electric Current -Important Questions & Preparation Tips

Jul 22, 2013 14:33 IST

In this article you will get the clue that from where and how the questions are being framed from the chapter Magnetic Effect of Electric Current
The experts of jagranjosh.com have full confidence that you will not miss any of the questions in the board exam as well as in competitive exams from this chapter if you will keep the following terms / question in your mind while studying

• Magnetic field. How can the direction of field lines at a place be determined?
• Magnetic field lines do not intersect each other. Explain.
• Properties of the Magnetic field lines
• When an electric current is passed through any wire, a magnetic field is produced around it. then why an electric iron connecting cables does not attract nearby  iron objects when electric current is switched on though it?
• A freely suspended magnet always point in north-south direction. Explain
• State and explain the clock face rule for determining the polarities of a circular wire carrying current.
• What are the factor affecting the strength of an electromagnet.
• Difference between a bar magnet and electromagnet
• What is solenoid? Diagram for magnetic field due to current carrying solenoid. Uses of solenoid.
• Difference between bar magnet and company Magnet
• Clock face rule. The process of determining the polarities of a circular wire carrying current through clock face rule.
• What Type of core should be put inside a current carrying solenoid to make an electromagnet?
• As magnetic field has Magnitude as well as direction. Explain.
• No two magnetic field lines are found to cross each other. Explain
• Importance of MRI for human body
• How to locate a current wire concealed in a wall.
• Explain- No force acts on a current carrying conductor when it is parallel to the magnetic field.
• Explain Flemings’ left hand rule for the direction of force.
• On what principal does motor work?
• With diagram the working of electric motor?
• How will you find the direction if a current carrying conductor is placed in a perpendicular field.
• Special features of commercial electric motor.
• Example of electromagnetic induction
• How can we increase the magnitude of current induced in the coil.
• What is electric generator and its principal.
• Two circular coils A and B are placed close to each other. If the current in coil A is change, will some current be induced in coil B? Give reason.
• AC generator and its diagram, explain its construction and working of AC generator
• Why the direction of induced current in the coil of an AC generator changes after direction showing the production of the coil.
• What normally drives the alternators in a thermal power station? What fuels can be used to heat water in the boiler?
• A circuit has fuse of a 5 A. what is the maximum number of 100 W (220 V) bulbs that can be safely used in the circuit?
• How is earthing of electric appliances done?
• What type of electric fuse is used in electrical appliances like stereos? Explain with diagram.
• Difference between overloading and short- circuiting as used in domestic circuits.
• An air-conditioner of 3.2 kW power rating is connected to a domestic electric circuit having a current rating of 10 A. the voltage of power supply is 220 V. what will happen when this air- conditioner is switched on? Explain your answer.

Go through the some questions given here as example and get an idea that how questions can be framed

Q1. The correct field lines are

Q2. An electric current passes through a straight wire in the direction of south to north. Magnetic compasses are placed at points A and B as shown in the figure. What is your observation?

a. The needle will not deflect
b. Only one of the needles will deflect
c. Both the needles will deflect in the same direction
d. The needles will deflect in the opposite directions

Q3. 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
d. Relative strength of magnetic field is shown by the degree of closeness of the field lines

Q4. What would be the effect of replacing ordinary bulbs with CFLs?

a. CFLs give less light than regular bulb hence room would be less bright
b. CFLs use less electricity hence electric bill will be reduced
c. CFLs produce more heat hence chances of fire will be increased

Q5. A coil of insulated copper wire is connected to a galvanometer forming a loop and a magnet is
A: held stationary, B : moved away along its axis C : moved towards along its axis,  There will be induced current in

a. A only
b. A and B only
c. B and C only
d. A, B and C

Q6. If two circular coils can be arrange in any of the tree situations shown in the diagram below, then their mutual induction will be….

a. Maximum in situation (a)
b. Maximum in situation (b)
c. Maximum in  situation (c)
d. The same in all situations

Q7. The resistance of a copper wire 200 m long is 21 Q. if its thickness (diameter) is 0.44mm, its specific resistance is

a. 1.2 x 10~ 8 Q-m
b. 1.4 x 10~8 Q-m
c. 1.6 x 10”””Q-m
d. 1.8 x 10”8 Q-m

Q8. A magnetic field of 5 Tesla is produced by a long wire carrying a current of 5A at a point distance 2 m from it. If the distance is made four-fold, the magnetic field will be

a. 0.5 Tesla
b. 1.25 Tesla
c. 0.2 Tesla
d. 4 Tesla

Q9. A constant current flows in a horizontal wire in the plane of the paper from east to west as shown below, the direction of magnetic field at a point will be north to south

a. Directly above the wire
b. Directly below the wire
c. At a point located in the plane of the paper, on the north side of the wire
d. At a point located in the plane of the paper, on the south side of the wire

Q10. As shown in the diagram, there is a magnetic field within a region of space. The magnetic field strength is the greatest at

a. P
b. Q
c. R
d. S

Q11. The direction of induced curent is obtained by

a. Fleming's left-hand rule
b. Maxwell's right-hand thumb rule
c. Ampere's rule
d. Fleming's right-hand rule

Q12. A soft iron bar is introduced inside a current carrying solenoid. The magnetic field inside the solenoid

a. will become zero
b. will decrease
c. will increase
d. will remain unaffected

Q13. Which of the following diagrams correctly shows the magnetic field produced by a current-carrying wire?

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