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Description
Flashcards by Valerie Shepherd, updated more than 1 year ago
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Created by Valerie Shepherd
about 10 years ago
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| Question | Answer |
| What are the four fundamental forces? | 1. Electromagnetic Force 2. Strong Nuclear Force 3. Weak Nuclear Force 4. Gravity |
| What is the relationship between atoms and the following fundamental forces? (a) Electromagnetic Force (b) Strong Nuclear Force (c) Weak Nuclear Force | (a) Holds the electrons within the atom. (b) Binds the nucleus together (c) Responsible for radioactive decay |
| What occurs as a black body is heated? | The frequency and intensity of the light emitted increases. |
| Define: Quanta | Energy packets |
| Define: Photon | A quanta of light |
| What are the equations for the energy of a photon? |
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E.JPG (image/JPG)
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| What is the equation for the frequency of a photon? |
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| What must be exceeded for an electron to be ejected from a metal surface when illuminated? | The frequency of the photon must exceed the threshold frequency of the metal |
| Once a photocurrent is registered, what occurs when the following occur? (a) The light intensity is increased (b) The light frequency is increased | (a) The current increases (b) The kinetic energy of ejected electrons increases |
| How is electron kinetic energy measured? | A negative potential is applied to a collector plate which repels electrons and eventually becomes large enough to stop them (this is called the cut-off voltage or the stopping potential). |
| What are the equations for the kinetic energy of an ejected electron? |
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| What are the equations for the momentum of a scattered photon? |
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| Scattered possess ______ energy and _______ wavelengths compared to the incident photon. | (a) Reduced (b) Longer |
| Define: Ground state | The lowest orbital level (n=1) and therefore the orbital with the lowest energy. |
| Define: Excitation | If energy is added to an atom (through particle bombardment, photons, etc.) then the electrons absorb definite quanta and must go to a higher energy orbital. When it does this it is said to be in a state of excitation. |
| Define: Ionisation energy | If an atom absorbs too much energy then the outermost electron will be promoted completely away from the attraction of the nucleus and will be lost - this is called the ionisation energy. |
| What is the ionisation energy for Hydrogen? |
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| What is the equation for the energy of a quantum orbital? |
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| Define: Inertial Reference Frame | A frame in which Newton's First Law applies |
| What is Newton's Law of Inertia? | A body at rest or in constant motion will remain as such unless an external and unbalanced force is acted upon it. |
| Define: Relativity Principle | The laws of physics are the same in all inertial frames assuming that lengths, masses and time are the same in each frame. |
| What are the two postulates of special relativity? | 1. The laws of physics have the same form in all inertial frames. 2. Light propagates through empty space with a definite speed (c) independent of the speed of the source or observer. |
| In relativity, how is simultaneity defined? | Two events in a reference frame are simultaneous if light signals from the events reach an observer located halfway between the events at the same time. |
| What are the equations for time, mass and length dilation? |
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