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65 Cards in this Set
- Front
- Back
- 3rd side (hint)
State laws of reflection |
1) Incident ray, reflected ray, and normal at the point of incidence all lie in the same plane 2) Angle of incidence i = angle of reflection r |
Remember light rays that strike on a mirror |
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Characteristics of a plane mirror image |
1) Image is same size as object 2) Lterally inverted 3) Upright 4) Virtual 5) Distance from mirror to image = distance from mirror to object |
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Uses of mirrors |
- Vision testing (make letters and numbers appear further away) - Blind corner mirror - Instrument scale (Voltmeter - avoid parallex error) - Periscope - Teleprompter (Newsreading) - others : optical instruments like telescopes, overhead projectors, CD players |
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Define refraction |
The bending of light as light passes from one optical medium to another (Due to the change in speed of light at the boundary of the two different optical media) |
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State laws of refraction |
1) Incident ray, refracted ray, and normal all lie in the same plane 2) For 2 given media, the ratio if the sine of angle of i to the sine of angle of r is a constant. n= sin i/ sin r |
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Define optical centre |
Midpoint between surfaces of lens on its principal axis Rays passing through optical centre are not refracted |
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Define principal axis |
Horizontal line passing through optical centre of lens , perpendicular to vertical plane of lens |
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Uses of converging lenses |
- Magnifying glass - Liquid Crystal Display ( LCD) projector - Film camera - Visual correction for long sightedness ( 老花眼) |
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Define a wave |
A wave is a disturbance that transfers energy from one place to another without transferring matter during energy transfer. [A wave is made up of periodic motion (Periodic motion is motion repeated at regular intervals) ] |
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Define transverse waves |
Waves that travel perpendicular to the direction of the vibration |
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Define longitudinal waves |
Waves that travel parallel to the direction of the vibration |
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Define amplitude |
Maximum displacement of a point from its rest position |
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Define wavelength |
Shortest distance between any 2 points in phase |
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Define wavefront |
An imaginary line on a wave that joins all adjacent points that are in phase |
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Period of wave |
Time taken for 1 complete wave |
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Refractive index |
Ratio if speed of light in vacuum to speed of light in the medium. n = c/v
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Frequency of wave |
The number of complete waves per second (Hz) |
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Define Total internal reflection |
The complete reflection of a light ray inside an optically denser medium at its boundary with an optically less dense medium. |
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Conditions for TIR |
1) Light ray in optically denser medium strikes its boundary with an optically less dense medium 2) angle of i > angle of c of the optically denser medium. |
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Define critical angle |
The angle of i in an optically denser medium for which angle of refraction in the optically less dense medium is 90deg |
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Formula to find critical angle |
Sin c = 1/n n = 1/sin c |
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Uses of TIR |
1) Glass prisms - Binoculars - Periscopes - Single lens reflex cameras
2) Optical fibres • Telecommunications industry :) - Higher carrying capacity compared to copper wire - Less signal degredation compared to copper wire - lightweight - low cost
• Medical industry :)- High flexibility, use as endoscopes to see inside hollow organs like intestines |
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Define focal length ** |
f is the distance between optical centre C and focal point F |
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Define focal plane |
The plane that passes through focal point F and perpendicular to principal axis |
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Define focal point F |
The point at which all rays parallel to principal axis converge after refraction by lens |
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Wave speed v=f入 |
Distance travelled by a wave per second |
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Order of Electromagnetic spectrum (lowest to highest frequency) (longest to shortest wavelength) |
Radio waves Microwaves Infrared Visible light (red to purple) Ultraviolet X-rays Gamma rays |
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Properties if EM waves |
- Transverse waves - Can travel through vacuum - Transfer energy from one place to another - Travel at same speed of 3 x 10^8 m/s in vacuum - v=f入 applicable - Travelling from one medium to another, V and 入 change. f does not change. - Obeys laws of reflection/ refraction - Carry no electric charge |
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Applications of EM waves |
Radio: - radios
Microwave: - microwaves ovens, satellite tv, GPS (global positioning system)
Infrared radiation: - Remote controllers, ear thermometers, intruder alarms
Visible light: - optical fibres
UV radiation: - Sunbeds, sterilisation of equipment
X-rays: - Radiation therapy (kill cancer cells), airport detection imaging
Gamma rays: - Radiation therapy (treat cancer by killing cancer cells) |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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How do sound waves propagate ? |
- Compressions (regions where air pressure is higher than surrounding air pressure) - Rarefactions ( regions where air pressure is lower than surrounding air pressure) |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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How do sound waves propagate ? |
- Compressions (regions where air pressure is higher than surrounding air pressure) - Rarefactions ( regions where air pressure is lower than surrounding air pressure) |
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Can sound be transmitted through vacuum? Why? |
No. Sound waves need a medium to travel. Like EM waves. |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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How do sound waves propagate ? |
- Compressions (regions where air pressure is higher than surrounding air pressure) - Rarefactions ( regions where air pressure is lower than surrounding air pressure) |
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Can sound be transmitted through vacuum? Why? |
No. Sound waves need a medium to travel. Like EM waves. |
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Speed of sound in S/L/G |
Gas -> Liquid -> Solid Slowest ---> Fastest |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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How do sound waves propagate ? |
- Compressions (regions where air pressure is higher than surrounding air pressure) - Rarefactions ( regions where air pressure is lower than surrounding air pressure) |
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Can sound be transmitted through vacuum? Why? |
No. Sound waves need a medium to travel. Like EM waves. |
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Speed of sound in S/L/G |
Gas -> Liquid -> Solid Slowest ---> Fastest |
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Define echo? |
Repetition of sound due to reflection of sound. |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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How do sound waves propagate ? |
- Compressions (regions where air pressure is higher than surrounding air pressure) - Rarefactions ( regions where air pressure is lower than surrounding air pressure) |
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Can sound be transmitted through vacuum? Why? |
No. Sound waves need a medium to travel. Like EM waves. |
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Speed of sound in S/L/G |
Gas -> Liquid -> Solid Slowest ---> Fastest |
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Define echo? |
Repetition of sound due to reflection of sound. |
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Formula of speed of sound involving echo |
v = 2d / t |
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Define sound |
Form of energy that is transferred from one point to another as a longitudinal wave. |
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How do sound waves propagate ? |
- Compressions (regions where air pressure is higher than surrounding air pressure) - Rarefactions ( regions where air pressure is lower than surrounding air pressure) |
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Can sound be transmitted through vacuum? Why? |
No. Sound waves need a medium to travel. Like EM waves. |
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Speed of sound in S/L/G |
Gas -> Liquid -> Solid Slowest ---> Fastest |
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Define echo? |
Repetition of sound due to reflection of sound. |
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Formula of speed of sound involving echo |
v = 2d / t |
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Uses of echoes |
- Measure large distance - detect location if objects |
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Define ultrasound |
Sound with frequencies above upper limit of human range of audibility ( 20 000Hz) |
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Define ultrasound |
Sound with frequencies above upper limit of human range of audibility ( 20 000Hz) |
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Uses of ultrasound |
- Quality control to check for cracks in concrete slabs - Prenatal scanning |
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Define ultrasound |
Sound with frequencies above upper limit of human range of audibility ( 20 000Hz) |
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Uses of ultrasound |
- Quality control to check for cracks in concrete slabs - Prenatal scanning |
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Define pitch |
Related to frequency of sound wave Higher frequency, higher pitch |
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Define Loudness |
Related to amplitude of sound wave Larger amplitude, louder the sound. |
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Define wave speed |
V is the distance travelled by a wave per second |
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