If a particle and antiparticle are in the appropriate quantum states, then they can annihilate each other and produce other particles.

If denotes the quantum state of a particle ( n ) with momentum p, spin J whose component in the z-direction is σ, then one has

If the path of the particle or centre of mass of the rigid body passes through the given origin, its angular momentum is zero.

If we define r < sub > i </ sub > as the displacement of particle i from the center of mass, and v < sub > i </ sub > as the velocity of particle i with respect to the center of mass, then we have

If we think of the atoms as impenetrable steel discs and the impinging particle as a bullet of negligible diameter, this ratio is the probability that the bullet will strike a steel disc, i. e., that the atomic projectile will be stopped by the foil.

If this acceleration is multiplied by the particle mass, the leading term is the centripetal force and the negative of the second term related to angular acceleration is sometimes called the Euler force.

If the depletion layer is large enough to catch the whole shower or to stop a heavy particle, a fairly accurate measurement of the particle ’ s energy can be made, simply by measuring the charge conducted and without the complexity of a magnetic spectrometer, etc.

If an elementary particle truly has no substructure, then it is one of the basic building blocks of the universe from which all other particles are made.

If the entire volume of the observable universe ( taken to be 3 × 10 < sup > 80 </ sup > m < sup > 3 </ sup >) were packed solid with fine dust particles about 1. 5 micrometres in size, then the number of different ways of ordering these particles ( that is, assigning the number 1 to one particle, then the number 2 to another particle, and so on until all particles are numbered ) would be approximately one googolplex.

If the particles are indistinguishable, this is impossible by definition ; either particle can be in either state.

If the particles are bosons, they occupy a totally symmetric state, which is symmetric under the exchange of any two particle labels:

If a particle of charge q moves with velocity v in the presence of an electric field E and a magnetic field B, then it will experience a force

If a force is applied to a particle for a time interval, the momentum of the particle changes by an amount

If the particle is moving at speed in the first frame of reference, in the second it is moving at speed

If a charged particle moves in an electromagnetic field, its kinematic momentum is not conserved.

If, e. g., u is the speed of a particle, then the straightforward notation for its velocity is u, < u > u </ u >, or.

If the photon energy is absorbed, some of the energy liberates the electron from the atom, and the rest contributes to the electron's kinetic energy as a free particle.

If the particle is in an eigenstate of position, then its momentum is completely unknown.

If the spin of a particle has a positive projection on its direction of motion then it is called left-handed ; otherwise, it is right-handed.

If Alice has a particle which is entangled with a particle owned by Bob, and Bob teleports it to Carol, then afterwards, Alice's particle is entangled with Carol's.

If you move them toward the beam, you count their value.

If he / she chooses not to put the detectors there, then the interference pattern will become reality ; if he / she does put the detectors there, then the beam path will become reality.

If the beam of light is not orthogonal ( or rather normal ) to the boundary, the change in wavelength results in a change in the direction of the beam.

If the surface has any transparent or translucent properties, it refracts a portion of the light beam into itself in a different direction while absorbing some ( or all ) of the spectrum ( and possibly altering the color ).

If the beam enters the sample perpendicular to the surface, then the activated region is uniform about the axis of the beam and a certain number of electrons " escape " from within the sample.

If one now shines a very intense beam of low-frequency light upon the same metal, a whole slew of electrons are ejected ; however they possess the same low energy, there are merely more of them.

If two points are connected by a wormhole, the time taken to traverse it would be less than the time it would take a light beam to make the journey if it took a path through the space outside the wormhole.

If the beam does not fill more than a third of the beam profiler ’ s sensor area, then there will be a significant number of pixels at the edges of the sensor that register a small baseline value ( the background value ).

If the baseline value is small or subtracted out, the knife-edge beam width always corresponds to 60 %, in the case of 20 / 80, or 80 %, in the case of 10 / 90, of the total beam power no matter what the beam profile.

If the beam has been collimated using a lens or other focusing element, the divergence expected can be calculated from two parameters: the diameter,, of the narrowest point on the beam before the lens, and the focal length of the lens,.

If we imagine the beam is made of photons, then every second numerous photons strike the surface and are absorbed.

If the particles become fast enough that relativistic effects become important, the beam becomes out of phase with the oscillating electric field, and cannot receive any additional acceleration.

If the beam struck the target, a " hit " was scored.

If she does not return to the beam within this time limit, she is not permitted to continue.

If the gymnast has not left the beam by 1: 30, another bell is sounded, and a score deduction is incurred.

If the motion goes far enough, this motion causes the lever arms to pull down on a thrust bearing, which moves a beam linkage, which reduces the aperture of a throttle valve.

If the Earth is traveling through an aether medium, a beam reflecting back and forth parallel to the flow of aether would take longer than a beam reflecting perpendicular to the aether because the time gained from traveling downwind is less than that lost traveling upwind.

If the equator is projected outward to the celestial sphere, forming the celestial equator, it crosses the ecliptic at two points known as the equinoxes.

: If a planet crosses ( or transits ) in front of its parent star's disk, then the observed brightness of the star drops by a small amount.

If an ineligible receiver is beyond the neutral zone when a forward pass which crosses the neutral zone is thrown, a foul of " ineligible receiver downfield " ( penalty — a loss of yardage, but not loss of down ) is called.

If one throws a hot gas with entropy into a black hole, once it crosses the horizon, the entropy would disappear.

If A is nonzero, then the x-intercept, that is, the x-coordinate of the point where the graph crosses the x-axis ( where, y is zero ), is − C / A.

If B is nonzero, then the y-intercept, that is the y-coordinate of the point where the graph crosses the y-axis ( where x is zero ), is − C / B, and the slope of the line is − A / B.

Hicks's stand-up routine was removed from the show allegedly because Letterman and his producer were nervous about a religious joke (" If Jesus came back he might not want to see so many crosses ").

If Tom crosses out that clause and writes "$ 7, 000 to Alice Johnson " in the margin, but does not sign or date the writing in the margin, most states would find that Tom had revoked the earlier provision, but had not effectively amended his will to add the second ; however, under DRR the revocation would be undone because Tom was acting under the mistaken belief that he could increase the gift to $ 7, 000 by writing that in the margin.

If the position of the earth in its orbit around the sun is reckoned with respect to the equinox, the point at which the orbit crosses the celestial equator, then its dates accurately indicate the seasons, that is, they are synchronized with the declination of the sun.

If the penetrator crosses their legs instead, it is called the lotus position.

If the receiver strikes the ball before it crosses a sideline or takes a second bounce on his or her side of the playing surface, the service is considered good and no let is called.

If a leshy crosses the path of a person in the woods, the person will get lost immediately.

* If a sleazy rumour crosses the room, it creates the same sort of clustering.

If the initial allocation is not at a point of tangency between an indifference curve of Octavio and one of Abby, then that initial allocation must be at a point where an indifference curve of Octavio crosses one of Abby.

If a wide ball crosses the boundary without touching the ground, only five wides ( not seven ) are scored-according to Law 19. 5, a boundary six can only be scored if the ball has touched the bat.

If there are warp floats on the technical face ( if the warp crosses over two or more wefts ), there will be filling floats ( the weft will cross over two or more warps ) on the technical back.

If one crosses Velyka Berdychivska Street from the southern end of Mykhailivska Street, then one finds oneself at Korolyov Square containing the building of the Zhytomyr Oblast Council.

If the receiver has skate contact with the red line at the instant the puck completely crosses it, the pass is legal regardless of where the puck actually makes contact with his stick.

If the receiver is moving with a velocity u through the fluid perpendicular to the wave fronts, the frequency received is determined by the proper time between the events where the receiver crosses crests.

If a duck target crosses the bottom row without being shot, it will come to life and begin flying down toward the player.

If a rock completely crosses the back line, it is removed from play

If at any point a member of the offense crosses the plane of the defensive team's circle ( with or without the ball ) the defense may call to account the transgression and demand an immediate turnover.

If the derivative of the curvature with respect to s is nonzero at P then the osculating circle crosses the curve C at P. Points P at which the derivative of the curvature is zero are called vertices.

If the source crosses a caustic, the deviations from a standard event can be large even for low mass planets.