Magnetic Field — Physics STD 12 Science — Question

The electric field at a point on equatorial line of a dipole and direction of the dipole moment:

Two spherical conductors A and B of radius a and b (b > a) are placed in air concentrically B is given charge + Q coulomb and A is grounded. The equivalent capacitance of these is

(a) 4π

(b) 4 π

(c) 4 π

(d) 4 π

A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in the negative X-direction. As a result, the charge will

(a) Remain unaffected

(b) Start moving in a circular path Y-Z plane

(c) Retard along X-axis

(d) Move along a helical path around X-axis

If   undergoes successively 8 a-decays and 6 b-decays, then resulting nucleus is

(a)

(b)

(c)

(d)

A particle has a velocity u towards east at t = 0. Its acceleration is towards west and is constant. Let x_A and x_B be the magnitude of displacements in the first 10 seconds and the next 10 seconds:

1. x_A < x_B
2. x_A = x_B
3. x_A > x_B
4. The information is insufficient to decide the relation of x_A with x_B.

Starting with a sample of pure    of it decays into Zn in 15 min. The corresponding half-life is

(a) 5 min

(b) 7  min

(c) 10 min

(d) 15 min

A solid sphere, a hollow sphere and a disc, all having same mass and radius, are placed at the top of an incline and released. The friction coefficients between the objects and the incline are same and not sufficient to allow pure rolling. Least time will be taken in reaching the bottom by:

1. The solid sphere.
2. The hollow sphere.
3. The disc.
4. All will take same time.

Liquids and gases never exhibit:

An electron of mass m when accelerated through a potential difference V has de-Broglie wavelength λ. The de-Broglie wavelength associated with a proton of mass M accelerated through the same potential difference will be

(a) λ

(b) λ

(c)  λ

(d)  λ