An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material. The material may either be composed solely of one ingredient or be a mixture containing at least two substances.
The potential energy stored in an explosive material may, for example, be:
An explosive lens—as used, for example, in nuclear weapons—is a highly specialized shaped charge. In general, it is a device composed of several explosive charges. These charges are arranged and formed with the intent to control the shape of the detonation wave passing through them. The explosive lens is conceptually similar to an optical lens, which focuses light waves. The charges that make up the explosive lens are chosen to have different rates of detonation. In order to convert a spherically expanding wavefront into a spherically converging one using only a single boundary between the constituent explosives, the boundary shape must be a paraboloid; similarly, to convert a spherically diverging front into a flat one, the boundary shape must be a hyperboloid, and so on. Several boundaries can be used to reduce aberrations (deviations from intended shape) of the final wavefront.
A grenade is a small explosive weapon typically thrown by hand (also called hand grenade), but can also refer to a shell (explosive projectile) shot from the muzzle of a rifle (as a rifle grenade) or a grenade launcher. A modern hand grenade generally consists of an explosive charge ("filler"), a detonator mechanism, an internal striker to trigger the detonator, an arming safety secured by a transport safety. The user removes the transport safety before throwing, and once the grenade leaves the hand the arming safety gets released, allowing the striker to trigger a primer that ignites a fuze (sometimes called the delay element), which burns down to the detonator and explodes the main charge.
Grenades work by dispersing fragments (fragmentation grenades), shockwaves (high-explosive and stun grenades), chemical aerosols (smoke, gas and chemical grenades), fire (incendiary grenades) or a jet of molten metal (anti-tank grenades). Their outer casings, generally made of a hard synthetic material or steel, are designed to rupture and fragment on detonation, sending out numerous fragments (shards and splinters) as fast-flying projectiles. In modern grenades, a pre-formed fragmentation matrix inside the grenade is commonly used, which may be spherical, cuboid, wire or notched wire. Most anti-personnel (AP) grenades are designed to detonate either after a time delay or on impact.
A touch hole, also known as a cannon vent, is a small hole at the rear (breech) portion of the barrel of a muzzleloading gun or cannon. The hole provides external access of an ignition spark into the breech chamber of the barrel (where the combustion of the propellant occurs), either with a slow match (matchlock), a linstock or a flash pan ignited by some type of pyrite- (wheellock) or flint-based gunlock (snaplock, snaphaunce, and flintlock), which will initiate the combustion of the main gunpowder charge. Without a touch hole, it would be nearly impossible to ignite the powder because the only otherwise access into the barrel is from the front via the muzzle, which is obturated by the projectile.
In the later caplock firearms, the ignition sparks are generated by a shock-sensitive percussion cap placed over a conical "nipple", which has a hollow conduit known as the flash channel, that leads into the barrel and serves the same function as the touch hole.