Gloved hand holding a Petri dish cover with a biohazard sticker. The Petri dish contains cell culture medium.

Colorless or white light as perceived by human eye actually consists of many colors or wavelengths of light. Photographed here is a beam of white light that is dispersed (decomposed) into different colors by an equilateral glass prism.

Myopic spectacles with a Snellen eye chart in the background

A ball-and-stick molecular model surrounded by several laboratory glass flasks.

Injectable medications in sealed vials and a disposable plastic medical syringe.

Hydrocodone is an opioid derived from codeine and thebaine. Hydrocodone is an orally active narcotic analgesic (pain reliever) and antitussive (cough suppressant). Shown here are generic pills that contain 10 mg of hydrocodone and 325 mg of acetaminophen (paracetamol). The trade name for this combination is Norco.

Results of automated DNA sequencing are displayed on the screen of a tablet computer.

A precision micropipette is used to transfer a small amount of liquid to a test tube with a green leaf. Out-of-focus laboratory glassware is in the frame.

Several pH indicators are added to several solutions in a multiwell plate. The indicators change their color depending on the pH of the solution.

0.1 M solution of iron(III) chloride is added to a beaker with 0.1 M solution of potassium thiocyanate (KSCN). Red-colored thiocyanatoiron(III) complex ion ([Fe(SCN)]2+) is produced. This reaction can be used as a test for Fe3+ ions in a solution.

Oxides of several metals in various containers. In focus is lead(II) oxide (PbO) in a watch glass.

Erlenmeyer flask containing a solution of potassium permanganate (KMnO4), surrounded by various flasks with transition metal salts, dry chemicals and solutions. Compounds containing transition metals are often colored.

A laptop computer, acoustic stethoscope, and a smart phone that displays an EKG trace.

Gloved hands are using a smartphone that displays a Magnetic Resonance Imaging (MRI) image of a knee. An acoustic stethoscope is in the background.

When light is incident from the air on an acrylic block it refracts (bends) toward the normal to the surface. When light exits the block through the second surface it refracts away from the normal to the surface. The angles of incidence and refraction are related through the Snell's law and depend on the refractive index of the block.

After a plastic comb is used for straightening dry hair (or rubbed on wool) it becomes electrically charged. The charge creates an electric field which then induces charge separation in nearby paper bits thus leading to a net electrostatic attractive force between the bits and the comb.

Interference between two laser beams, as could be observed using Michelson interferometer with a red Helium-Neon laser. Single laser beam is split into two beams which are then recombined and crossed at a small angle to each other. The interference fringes are observed in a plane perpendicular to the beams' propagation direction. Conceptually, this is a modern-day replication of Thomas Young's double-slit experiment.

Iron shavings are used to reveal magnetic field lines produced by a bar magnet.

A pencil is placed behind an acrylic rectangular block. The pencil appears to be "broken" because of optical refraction due to the difference in the refractive index between acrylic and air.

Colorless or white light as perceived by human eye actually consists of many colors or wavelengths of light. Optical intensity as a function wavelength is called spectral distribution or spectrum. Shown here is the spectrum of white light emitted by an incandescent bulb filament. The spectrum was obtained by decomposing or spatially dispersing white light with a diffraction grating. Note that emission of the incandescent bulb covers visible spectrum continuously.

A red laser beam is incident on a tank of water from the left. The beam is totally internally reflected at the water-air interface. Total internal reflection occurs when light is incident on an interface between a more optically dense medium and a less optically dense medium and the angle of incidence exceeds a certain value, called critical angle.

Spoon in a cup of water is used to demonstrate optical refraction due to the difference in the refractive index between water and air.

A demonstration pendulum made of an aluminum weight suspended by a string from a pivot point.

Newton rings is an interference pattern between a spherical and a plane wavefronts.