A long wire carries a steady current. It is bent into a circle o

Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

21.

A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then

  • its velocity will decrease.

  • its velocity will increase.

  • it will turn towards right of direction of motion.

  • it will turn towards right of direction of motion.

135 Views

22.

A charged particle of mass m and charge q travels on a circular path of radius r that is perpendicular to a magnetic field B. The time taken by the particle to complete one revolution is

  • fraction numerator 2 πmq over denominator straight B end fraction
  • fraction numerator 2 πq squared straight B over denominator straight m end fraction
  • fraction numerator 2 πqB over denominator straight m end fraction
  • fraction numerator 2 πqB over denominator straight m end fraction
158 Views

23.

In a potentiometer experiment, the balancing with a cell is at length 240 cm. On shunting, the cell with a resistance of 2Ω the balancing length becomes 120 cm. The internal resistance of the cell is

  • 1 Ω

  • 0.5 Ω

  • 3 Ω

  • 3 Ω

166 Views

24.

The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 W and 200 V lamp when not in use?

  • 40 Ω

  • 20 Ω

  • 400 Ω

  • 400 Ω

145 Views

Advertisement
25.

A magnetic needle is kept in a non-uniform magnetic field. It experiences

  • a torque but not a force

  • neither a force nor a torque

  • a force and a torque.

  • a force and a torque.

101 Views

26.

A current I ampere flows along an infinitely long straight thin-walled tube, then the magnetic induction at any point inside the tube is

  • infinite

  • zero

  • fraction numerator straight mu subscript 0 over denominator 4 straight pi end fraction fraction numerator 2 straight i over denominator straight r end fraction space tesla
  • fraction numerator straight mu subscript 0 over denominator 4 straight pi end fraction fraction numerator 2 straight i over denominator straight r end fraction space tesla
452 Views

Advertisement

27.

A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is B. It is then bent into a circular loop of n turns. The magnetic field at the centre of the coil will be

  • nB

  • n2B

  • 2nB

  • 2nB


B.

n2B

The magnetic field at the centre of circular coil is



When wire of length i bents into a circular loops of n turns, then

l = n × 2 π r

⇒ r = 1/ n x 2 π

Thus, new magnetic field

1355 Views

Advertisement
28.

The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 µT. What will be its value at the centre of the loop?

  • 250 µT

  • 150 µT

  • 125 µT

  • 125 µT

625 Views

Advertisement
29.

In a uniform magnetic field of induction B a wire in the form of semicircle of radius r rotates about the diameter of the circle with angular frequency ω. The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R the mean power generated per period of rotation is

  • fraction numerator Bπr squared space straight omega over denominator 2 straight R end fraction
  • fraction numerator left parenthesis Bπr squared straight omega right parenthesis squared over denominator 2 straight R end fraction
  • fraction numerator left parenthesis Bπrω squared right parenthesis over denominator 2 straight R end fraction
  • fraction numerator left parenthesis Bπrω squared right parenthesis over denominator 2 straight R end fraction
571 Views

30.

A charged oil drop is suspended in a uniform field of 3 × 104 V/m so that it neither falls nor rises. The charge on the drop will be (take the mass of the charge = 9.9 × 10−15 kg and g = 10 m/s2 )

  • 3.3 × 10−18 C

  • 3.2 × 10−18 C

  • 1.6 × 10−18 C

  • 1.6 × 10−18 C

155 Views

Advertisement