Multiple Choice Questions : Physics Class X
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MAGNETIC EFFECTS OF ELECTRIC CURRENT
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1.A magnetic field can exert force on
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(a)a moving magnet (b) stationary magnet (c) moving charge (d)all of these
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2.Magnetic lines of force
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(a)have more directions (b)have no physical reality
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(c)can be used to indicate the direction of the magnetic field of a point
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(d)all the above
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3. When is the back emf of an electric motor the greatest?
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(a)when the motor is witched on
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(b)when the motor is speeding up
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(c)when the motor is at maximum speed
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(d)when the motor is slowing down
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4.According to international convention of color coding in a wire
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(a)live is red, neutral is black and earth is green
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(b) live is brown, neutral is blue and earth is green
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(c) live is brown, neutral is green and earth is black
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(d)live is red, neutral is yellow and earth is blue
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5.An electric current can be produced in a closed loop
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(a)by connecting it to a battery, but not by moving a magnet near it
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(b)by moving a magnet near it, but not by connecting it to a battery
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(c)by connecting it to a battery, as well as by moving a magnet near it
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(d)neither by connecting it to battery nor by moving a magnet near it
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6.Which of the following describes the common domestic power supplied in India?
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(a)220V,100Hz (b)110V,100Hz
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(c)220V,50Hz (d)110V,50Hz
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7.Magnetic field due to a current carrying straight wire depends on
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(a)current only (b)distance from the wire only
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(c) both a) and (b) (d)none
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8.The direction of the magnetic field produced by a current carrying straight conductor can be found using
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(a)right hand thumb rule (b)right hand Fleming’s rule
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(c)left hand Fleming’s rule (d)right hand screw rule
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9.A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each
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(a)two revolution (b)one revolution (c)half revolution (d)one-forth revolution
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10.Electric motor
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(a)is based on electromagnetic induction (b)converts kinetic energy into electrical energy
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(c)converts electric energy into kinetic energy (d)none
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11.To convert ac generator into dc generator
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(a)split ring type commentator must be used (b)slip rings and brushes must be used
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(c)a stronger magnetic field has to be used (d)a rectangular wire loop has to be used
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12.Choose the incorrect statement
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(a)The direction of magnetic field at a point is taken to be the direction in which north pole of magnetic compass needle points
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(b)magnetic field lines are closed curves
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(c)If magnetic field lines are parallel and equi distant, they represent zero field strength
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(d)relative strength of magnetic field is shown by the degree of closeness of the field lines.
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13.Force on a current conductor in a magnetic field depends on
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(a)length of the conductor (b)current in the conductor
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(c)magnitude of the magnetic field (d)all of these
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14.Magnetic field inside a solenoid is
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(a)non-uniform (b)circular
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(c)uniform (d)none
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15.Magnetic field lines due to a bar magnet is similar to that of a
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(a)current carrying straight wire (b) solenoid (c) two parallel wires (d)none
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