Atoms — Physics STD 12 Science — Question

In a semiconductor diode, the barrier potential offers opposition to:

In a purely inductive circuit, the current:

In the ideal double-slit experiment, when a glass-plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams (wavelength l), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is

(a) 2l

(b)

(c)

(d)

A dip circle is so set that its needle moves freely in the magnetic meridian. In this position, the angle of dip is 40º. Now the dip circle is rotated so that the plane in which the needle moves makes an angle of 30º with the magnetic meridian. In this position, the needle will dip by an angle:

Assertion  :  The drift velocity of electrons in a metallic wire will decrease, if the temperature of the wire is increased.

Reason      : On increasing temperature, conductivity of metallic wire decreases.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Which one of the following has the shortest wavelength?

Consider a photon of a continuous X-ray coming from a Coolidge tube. Its energy comes from:

Radius of  nucleus is 3 Fermi. The radius of  nucleus will be

(a) 5 Fermi

(b) 6 Fermi

(c) 11.16 Fermi

(d) 8 Fermi

Transformers are used:

1. In DC circuits only.
2. In AC circuits only.
3. In both DC and AC circuits.
4. Neither in DC nor in AC circuits.

How is the electric field between the two plates of a parallel plate capacitor?