A neutron, a proton, an electron and an α-particle enter a region of uniform magnetic field with the same velocities. The magnetic field is perpendicular and directed into the plane of the paper. The tracks of the particles are labelled in the figure. The electron follows the track.

• A

• B

• C

• D

The deflection in a moving coil galvanometer is reduced to half when it is shunted with a 40 Ω coil. The resistance of the galvanometer

• 80 Ω

• 40 Ω

• 20 Ω

• 15 Ω

A current of $\left(\frac{2}{\sqrt{3}}\right)$ A, produces a deflection of 60° in a tangent galvanometer. The reduction factor is

• $\left(\frac{2}{\sqrt{3}}\right) \mathrm{A}$

• $\left(\frac{2}{3}\right) \mathrm{A}$

• 2 A

• $\left(\frac{3}{2}\right) \mathrm{A}$

Pick out the wrong statement.

• An electron at rest experiences no force in the magnetic field

• The gain in the KE of the electron moving at right angles to the magnetic field is zero

• When an electron is shot at right angles to the electric field, it traces a parabolic path

• An electron moving in the direction of the electric field gains KE

Magnetic field at a distance r from an infinitely long straight conductor carrying a steady current varies as

• $\frac{1}{\sqrt{\mathrm{r}}}$

• $\frac{1}{{\mathrm{r}}^2}$

• $\frac{1}{\mathrm{r}}$

• $\frac{1}{{\mathrm{r}}^3}$

An α-particle and a proton moving with the same kinetic energy enter a region of uniform magnetic field at right angles to the field. The ratio of the radii of the paths of α-particle to that of the proton is

• 1 : 8

• 1 : 1

• 1 : 2

• 1 : 4

Direction of current induced in a wire moving in a magnetic field is found using

• Right hand clasp rule

• Fleming's left hand rule

• Fleming's right hand rule

• Ampere's rule

A proton and helium nucleus are shot into a magnetic field at right angles to the field with same kinetic energy. Then the ratio of their radii is

• 1 : 1

• 1 : 2

• 2 : 1

• 1 : 4

Two tangent galvanometers, which are identical except in their number of turns, are connected in parallel. The ratio of their resistances of the cols is 1 : 3. If the deflections in the two tangent galvanometers are 30° and 60° respectively, then the ratio of their number of turns is

• 1 : 1

• 3 : 1

• 1 : 3

• 1 : 6

140.

A charged particle with a velocity 2 x 10³ ms^-1 passes undeflected through electric field and magnetic fields in mutually perpendicular directions. The magnetic field is 1.5 T. The magnitude of electric field will be

• 1.5 × 10³ NC^-1

• 2 × 10³ NC^-1

• 3 × 10³ NC^-1

• 1.33 × 10³ NC^-1