Write the expression for the Lorentz force F in vector form. f

Subject

Physics

Class

ICSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Choose the correct alternative (a), (b), (c) or (d) for the question given below:

In the figure, a charge Q is fixed. another charge q s moved along a circular arc MN of radius r around it, from the point M to the point N such that the length of the arc MN = l. The work done in this process is:

  • zero

  • Error converting from MathML to accessible text.
  • Error converting from MathML to accessible text.
  • fraction numerator Qq over denominator 2 πε subscript straight o straight r squared end fraction

2.

A carbon resistor has coloured bands as shown in fig. 2 below. The resistance of the resistor is:

  • 26 straight capital omegaplus-or-minus 10%

  • 26 straight capital omegaplus-or-minus 5%

  • 260 straight capital omegaplus-or-minus 5%

  • 260 straight capital omegaplus-or-minus 10%


3.

A solenoid L and a resistor R are connected in series to a battery, through a switch. When the switch is put on, current I flowing through it varies with time t as shown in which of the graphs given below:


4.

Two thin lenses having optical powers of -10 D and +6 D are placed in contact with each other. The focal length of the combination is:

  • +0.25 cm

  • -0.25 cm

  • +0.25 cm

  • -0.25 m


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5.

Total energy of an electron in the ground state of hydrogen atom is -13.6 eV. Its total energy, when hydrogen atom is in the first excited state, is:

  • +13.6 eV

  • +3.4 eV

  • -3.4 eV

  • -54.4 eV


 Multiple Choice QuestionsShort Answer Type

6.

A charged oil drop weighing 1.6 x 10-15 N is found to remain suspended in a uniform electric field intensity 2 x 103 NC-1. Find the charge on the drop?


7.

For a metallic conductor, what is the relation between current density (J), conductivity (straight sigma) and electric field Intensity (E)?


8.

In the figure given below, find the value of resistance X for which points A and B are at the same potential:


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9.

Write the expression for the Lorentz force F in vector form.


Lorentz force is given by,

straight F with rightwards harpoon with barb upwards on top space equals space q space open parentheses V with rightwards harpoon with barb upwards on top space x space B with rightwards harpoon with barb upwards on top close parentheses
where, straight v with rightwards harpoon with barb upwards on top is the velocity of the charged particle, and
straight B with rightwards harpoon with barb upwards on top is the magnetic field.


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10.

A coil has self-inductance of 0.05 Henry. Find the magnitude of the emf induced in it when the current flowing through it is changing at the rate of 100 A s-1.


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