Controlling what is lit and what is not lit is important to the look of a shot.  What is it you are trying to control and list three ways to control it.

Soft boxes use this to control unwanted light from spreading:

A high contrast style of lighting means using this technique on faces of characters.

To draw an audience into part of a specific character’s face, the DP will most often call for the light to be on the smart side which means: 

This type of light will cast the sharpest – well defined shadows:

A uniform sign is supported against a wall at point P as shown in the figure. If the sign is a square 0.40 m on a side and its mass is 4.0 kg. What is the magnitude of the horizontal force that the wall at P experiences?

A potter’s wheel, with rotational inertia 48 kg∙m2, is spinning freely at 40 rpm. The potter drops a lump of clay onto the wheel, where it sticks a distance 1.2 m from the rotational axis. If the subsequent angular speed of the wheel and clay is 32 rpm what is the mass of the clay?

Platinum Testing   Click the link then choose Block Exam #2 Respiratory.

For hydrogen, what is the wavelength of the photon emitted when an electron drops from a 3d orbital to a 2p orbital in a hydrogen atom? The Rydberg constant is 1.097 × 10-2 nm-1.

What is the de Broglie wavelength of a helium nucleus (m = 6.646 × 10-27 kg) with a velocity of 1.89 × 106 m/sec?