Solution:
X-rays and gamma rays are photons, i.e. high energy light-waves. When emitted by a source, for example, radium or cobalt, located outside the body, they easily pass through the body, hence they are usually called penetrating radiation. Because X-rays are penetrating, they can be used in diagnostic medicine to image human bones or human organs made opaque by a dye.

Solution:
The bending of light (i.e. refraction of light) as it moves from water to air makes the water tank appear to be less shallower than its real depth.

Solution:
Hydraulic brakes in automobile work on Pascal's principle.

Solution:
When detergent is added to water, it decreases the surface tension of the water. Compounds that lower water's surface tension are called surfactants, which work by separating the water molecules from one another.

Solution:
The SI unit of dynamic viscosity is the newton-second per square meter.

Solution:
Particle physics studies the nature of particles, while nuclear physics studies the atomic nuclei.

Solution:
Hertz is the SI unit of frequency.