Answer:
The current through it will also decrease to half of its former value because according to Ohm's law the current flowing through a resistor is directly proportional to the potential difference applied across its ends provided that the temperature and some other necessary conditions remain constant.
This is mathematically represented as follows;

The current is thus given as

if R is constant and V is reduced to half, then we have the following;

Simplifying further we obtain

Equation (3) shows that the current I is also reduced to half.
Fresnel and Fraunhofer diffraction. Fresnel diffraction is produced when light from a point source meets an obstacle, the waves are spherical and the pattern observed is a fringed image of the object. Fraunhofer diffraction occurs with plane wave-fronts with the object effectively at infinity. The pattern is in a particular direction and is a fringed image of the source.