MAGNETIC EFFECTS OF ELECTRIC CURRENT - I :MCQs AND SHORT ANSWERS

MULTIPLE-CHOICE QUESTIONS

*INDEX-TOPIC SEARCH

SELECT THE CORRECT ALTERNATIVE:

1. Who was the first person to notice the magnetic effect of electric current ?
   
   
   
   1. Faraday
   2. Ampere
   3. Oersted
   4. Volta
      
   
   
2. The magnetic field produced due to the current passing through a conductor is proportional to the _______.
   
   
   
   1. electric current
   2. conducting material
   3. length of conductor
   4. diameter of conductor
      
   
   
3. The magnetic field produced at the center of a circular wire is proportional to _______ and inversely proportional to _______.
   
   
   
   1. radius of loop, current
   2. current, radius of loop
   3. length of conductor, current
   4. weight of conductor, current
      
   
   
4. The magnetic field of a solenoid is quite similar to that of
   
   
   
   1. a straight conductor
   2. a horse-shoe magnet
   3. a bar magnet
   4. any magnet
      
   
   
5. The principle of magnetic induction was given by _______.
   
   
   
   1. Michael Faraday
   2. Galileo
   3. Oersted
   4. Ampere
      
   
   
6. The direction of a magnetic field is taken _______.
   
   
   
   1. north to south and back
   2. south to north and back
   3. north to south only
   4. south to north only
      
   
   
7. What is the frequency of the current used domestically in India ?
   
   
   
   1. 50 Hz
   2. 60 Hz
   3. 110 Hz
   4. 220 Hz
      
   
   
8. In our domestic electric supply we use following three colours of wire.
   
   
   
   1. red, blue, green
   2. red, yellow, blue
   3. red, black, green
   4. black, green, yellow
      
   
   
9. The insulation cover on the earth wire is _______.
   
   
   
   1. red
   2. black
   3. green
   4. white
      
   
   
10. The current passing through two separate lines (circuits) of our houses is _______ A and _______ A.
    
    
    
    1. 5, 10
    2. 5, 15
    3. 10, 15
    4. 2, 5
       
    
    
11. The direction of magnetic field lines is taken
    
    
    
    1. north to south
    2. south to north
    3. entering both poles
    4. leaving both poles
       
    
    
12. The magnetic field due to electric current in a conductor is _______.
    
    
    
    1. in the direction of electric current
    2. in the direction opposite to electric current
    3. circular around the conductor
    4. in the center of the conductor
       
    
    
13. Which device is used to convert electric energy into mechanical energy ?
    
    
    
    1. electric generator
    2. solenoid
    3. electric motor
    4. electric iron
       
    
    
14. The principle of electric generator is _______.
    
    
    
    1. conversion of electrical energy into mechanical energy
    2. conversion of electrical energy into thermal energy
    3. conversion of mechanical energy into electrical energy
    4. conversion of electrical energy into light energy
       
    
    
15. Magnetic lines of force inside a solenoid are...
    
    
    
    1. from N to S
    2. from S to N
    3. circular
    4. intersect one another
       
    
    

ANSWERS


(1) C (2) A (3) B (4) C (5) A (6) C (7) A (8) C (9) C (10) B (11) A (12) C (13) C (14) C (15) B

SHORT QUESTIONS

ANSWER IN SHORT:

1. Who provided the first evidence of connection between electricity and magnetism ? When ?
   
        ANS :Danish physicist H.C.Oersted in 1820 AD provided the first evidence of connection between electricity and magnetism.
   
2. Why is a magnetic needle placed near a current carrying conductor deflected ?
   
        ANS : A magnetic needle placed near a current carrying conductor is deflected because the current carrying conductor possesses a magnetic field.
   
3. State the Right-hand Thumb Rule.
   
        ANS : Hold the conducting wire in the right hand such that the thumb is stretched along the direction of the current, then the fingers will wrap around the conductor in the direction of the magnetic field.
   
4. What is a solenoid /
   
        ANS : A coil of many turns of wire wrapped in the shape of a cylinder is called a solenoid.
   
5. What is 'induced electric current'?
   
        ANS : The electric current produced in a loop of conductor due to the relative motion of a magnet within the loop(coil) is called induced electric current.
   
6. What is electromagnetic induction ?
   
        ANS : Electromagnetic induction is the production of electromotive force(voltage) in a conductor when there is relative motion of the conductor within a magnetic field.
   
7. What is an electric motor ?
   
        ANS : An electric motor is a device that converts electrical energy into mechanical energy.
   
8. Write the principle of electric motor.
   
        ANS : An electric motor converts electrical energy into mechanical energy by using the principle that in an electric field the current-carrying conductor experiences force.
   
9. What is an armature ?
   
        ANS : A loop(coil) wound on an axis along with the commutator is known as an armature.
   
10. Name some gadgets where an electric motor is used.
    
         ANS : Fan, mixer, washing machine, fridge, water pump, etc.are examples of gadgets where an electric motor is used.
    
11. What is an electric generator ?
    
         ANS : An electric generator is a device which converts mechanical energy into electrical energy.
    
12. On which principle does an electric generator work ?
    
         ANS : An electric generator works on the principle of electromagnetic induction.
    
13. Mention two types of current.
    
         ANS : The two types of current are :(i) Direct Current, DC (ii) Alternating Current, AC.
    
14. What is direct current ?
    
         ANS : If in a circuit, the current flows from the positive terminal to the negative terminal(i.e. only in one direction) of the battery, the current is called direct current(DC).
    
15. What is alternating current ?
    
         ANS : If in a circuit the voltage and current change their direction between positive and negative terminals periodically with the time, the current is called alternating current(AC).
    
16. Which type of current is supplied/used in domestic lines ?
    
         ANS : Alternating current(AC) is supplied in domestic lines.
    
17. What do we mean by frequency of current ?
    
         ANS : The number of times an alternating current in a circuit changes its direction per second is called the frequency of that current.
    
18. What is the unit of frequency of current ?
    
         ANS : 'Hertz' (Hz) is the unit of frequency of current.
    
19. What is the colour of insulation cover of a 'live wire' or 'phase wire'?
    
         ANS : Red is the colour of insulation cover of a 'live wire' or 'phase wire'.
    
20. Mention the colour of insulation cover of a 'neutral wire' or 'negative wire'.
    
         ANS : The colour of insulation cover of a 'neutral wire' is black.
    
21. To what is the earth wire connected ?
    
         ANS : The earth wire is connected to a metal plate deep in the earth near the house.
    
22. Which is the type of connection used for domestic wiring ?
    
         ANS : The type of connection used for domestic wiring is parallel connection.
    
23. How is an inductor shown in a circuit ?
    
         ANS : ΩΩΩ is the symbol to show an inductor in a circuit.
    
24. What does short-circuit mean ?
    
         ANS : Short-circuit means the positive and negative wires have come into contact with each other due to some fault.
    
25. What is overloading ?
    
         ANS : Overloading is the situation created when many appliances connected in a circuit draw much higher current than the electric line can hold.
    
26. What is a fuse ?
    
         ANS : A fuse is a device consisting of a wire made up of a low melting-point metal/alloy which melts during short-circuit or overloading and prevents accident as well as damage to costly appliances.
    
27. Which metal is generally used to make a fuse wire ?
    
         ANS : Fuse wires are generally made up of pure tin or an alloy of tin with other metals like copper.
    
28. What type of magnetic field arises when current passes through a linear wire ?
    
         ANS : A circular magnetic field( or a field comprising of concentric circles) arises around a linear wire when current passes through it.
    
29. In which part of solenoid do we find uniform magnetic field ?
    
         ANS : We find uniform magnetic field in the central(core) part of a solenoid.
    
30. What is an electromagnet ?
    
         ANS : An iron bar(core) with coils of wire wound around it,which acts as a temporary magnet when an electric current flows through the wire is called ELECTROMAGNET.
    
31. When will the current carrying wire experience maximum force in the magnetic field ?
    
         ANS :When it is placed perpendicularly to the magnetic field.
    
32. The frequency of alternating current is 50 Hz. What does it mean ?
    
         ANS :It means that the current changes its direction alternately 50 times between two terminals in one second.
    
33. 
    
         ANS :
    
34. 
    
         ANS :