41.

A capacitor is connected to a cell of emf E having some internal resistance r, The potential difference across the :

• cell is < E

• cell is E

• capacitor is > E

• capacitor is < E

An electron moves at a right angle to a magnetic field of 1.5 x 10^-2 tesla with a speed of 6 x 10⁷ m/s. If the specific charge of the electron is 1.7 x 10¹¹ coulomb/kg, the radius of the circular path will be

• 2.9 cm

• 3.9 cm

• 2.35 cm

• 2 cm

The figure shows three points A, B and C in a region of a uniform electric field $\overrightarrow{\mathrm{E}}$. The line AB is perpendicular and BC is parallel to the field lines. Then which of the following holds good?

• V_A = V_B = V_C

• V_A = V_B > V_C

• V_A = V_B < V_C

• V_A > V_B = V_C

The potential difference between points A and B is:

• 20/7 V

• 40/7 V

• 10/7 V

• zero

A short linear object of length b lies along the axis of a concave mirror of focal length f at a distance u from the pole of the mirror, what is the size of the image?

• $\left(\frac{\mathrm{f}}{\mathrm{u} - \mathrm{f}}\right)\mathrm{b}$

• ${\left(\frac{\mathrm{f}}{\mathrm{u} - \mathrm{f}}\right)}^2\mathrm{b}$

• $\left(\frac{\mathrm{f}}{\mathrm{u} - \mathrm{f}}\right){\mathrm{b}}^2$

• $\left(\frac{\mathrm{f}}{\mathrm{u} - \mathrm{f}}\right)$

The minimum wavelength of X-rays emitted by X-ray tube is 0.4125 Å. The accelerating voltage is :

• 30 kV

• 50 kV

• 80 kV

• 60 kV

An LC circuit is in the state of resonance. If C = 0.1 F and L = 0.25 H, neglecting ohmic resistance of the circuit, what is the frequency of oscillations?

• 1007 Hz

• 100 Hz

• 109 Hz

• 500 Hz

A bar magnet of magnetic moment $\overrightarrow{\mathrm{M}}$ is placed in the magnetic field $\overrightarrow{\mathrm{B}}$. The Torque acting on the magnet is :

• $\overrightarrow{\mathbf{M}} \times \overrightarrow{\mathbf{B}}$

• $\overrightarrow{\mathbf{M}} - \overrightarrow{\mathbf{B}}$

• $\frac{1}{2}\overrightarrow{\mathbf{M}} \times \overrightarrow{\mathbf{B}}$

• $\overrightarrow{\mathbf{M}} + \overrightarrow{\mathbf{B}}$

A capacitor of capacitance 6 µF is charged upto 100 volts. The energy stored in the capacitor is :

• 0.6 joule

• 0.06 joule

• 0.03 joule

• 0.3 joule

Find the equivalent resistance between the points A and B :

• 2 Ω

• 4 Ω

• 8 Ω

• 16 Ω