Electric Charges and Fields — Physics STD 12 Science — Question

A circular coil of conducting wire has an area A and number of turns N. It is lying in a vertical plane in a region where uniform magnetic field B exist with field direction normal to the coil plane. If the coil is rotated about a vertical axis by an angle π in 0.5 seconds, then the value of the emf induced at the ends of the coil is.

The time period of rotation of the sun is 25 days and its radius is 7 . The Doppler shift for the light of wavelength 6000 Å emitted from the surface of the sun will be

(a) 0.04 Å

(b) 0.40 Å

(c) 4.00 Å

(d) 40.0 Å

An electron revolves 6 × 10¹⁵ times/sec in circular loop.  The current in the loop is

(a) 0.96 mA

(b) 0.96 m A

(c) 28.8 A

(d) None of these

An electron is moving along the positive x-axis. You want to apply a magnetic field for a short time so that the electron may reverse its direction and move parallel to the negative x-axis. This can be done by applying the magnetic field along:

1. y-axis.
2. z-axis.
3. y-axis only.
4. z-axis only.

Two point charges q₁ and q₂ are situated at a distance d. There is no such point in between them where the electric field is zero. What can we deduce?

What is the net electrostatic field in the interior of a conductor?

The binding energy per nucleon of helium is :

In the Bohr's hydrogen atom model, the radius of the stationary orbit is directly proportional to (n = principle quantum number)

(a)

(b) n

(c)

(d)

The electric field intensity at a point in vacuum is equal to:

A proton and an electron are placed in a uniform electric field.