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

• 
• 
• 

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

• 26  10%

• 26  5%

• 260  5%

• 260  10%

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

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

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?

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

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

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

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.