Consider two rays which emerge making an angle with the straight through line. Constructive interference (brightness) will occur if the difference in their two path lengths is an integral multiple of their wavelength () i.e., difference = n where n = 1, 2, 3, ... Now, a triangle is formed, as indicated in the diagram, for which n = d sin( ) and this is known as the DIFFRACTION GRATING EQUATION. In this formula is the angle of emergence (called deviation, D, for the prism) at which a wavelength will be bright, d is the distance between slits (note that d = 1 / N if N, called the grating constant, is the number of lines per unit length) and n is the "order number", a positive integer (n = 1, 2, 3, ...) representing the repetition of the spectrum. Thus, the colors present in the light from the source incident on the grating would emerge each at a different angle since each has a different wavelength . Furthermore, a complete spectrum would be observed for n = 1 and another complete spectrum for n = 2, etc., but at larger angles. Also, the triangle formed by rays to the left of 0o is identical to the triangle formed by rays to the right of 0o but the angles R and L (Right and Left) would be the same only if the grating is perpendicular to the incident beam. This perpendicularity is inconvenient to achieve so, in practice, R and L are both measured and their average is used as in the grating equation. PROCEDURE Calibrating the Spectrometer Read and follow the procedures for calibrating the spectroscope found in the previous experiment. The calibration can be performed with the grating in place on the table. Measuring CAUTION: The diffraction grating is a photographic reproduction and should NOT be touched. The deeper recess in the holder is intended to protect it from damage. Therefore, the glass is on the shallow side of the holder and the grating is on the deep side. Place the grating on the center of the table with its scratches running vertically, and with the base material (glass) facing the light source. In this way, one can study diffraction without the complication of refraction (recall from the previous lab how light behaves when traveling through glass at other than normal incidence). Fix the grating in place using masking tape. Rotate the table to make the grating perpendicular to the incident beam by eye. This is not critical since the average of R and L accommodates a minor misalignment. Affirm maximum brightness for the straight through beam by adjusting the source-slit alignment. At this step, the slit should be narrow, perhaps a few times wider than the hairline. Search for the spectrum by moving the telescope to one side or the other. This spectrum should look much like that observed with the prism except that the order of the colors as you move away from zero degrees is reversed. Search for the second- and third-order spectra. Do not measure the higher-order angles, but record the order of colors away from zero degrees. For each of the seven colors in the mercury spectrum, measure the angles R and L to the nearest tenth of a degree by placing the hairline on the stationary side of the slit. Analysis Average the right and left angles for each color. Use the grating equation with d=(1/6000) cm to find the wavelength for each color. Remember that 108 angstrom = 1 cm. Calculate the percent deviation for each wavelength using % deviation = (data-theory)/theory x 100% where "theory" is the tabulated wavelength from the last experiment. Do not ignore the sign; it contains information. A positive % deviation means that the value is above the theory; a negative % deviation means that the value is below the theory. Do you notice any systematic problems in your seven % deviations? Use the grating equation with the tabulated values of from last time and your measured values of to calculate seven different values of N, the grating constant (N=1/d). Average the seven values of N. For the error on N, use the standard deviation on the mean (SDOM). Compare your answer to the accepted value of 6000 lines/cm. Does your value of N agree with the manufacturer's value within the error range? See Taylor page 5 if you are confused. What could be causing any discrepancy? Why is it necessary that the base side of the grating face toward the light source? Draw a ray diagram for the two cases: a) base toward the source (correct) and b) grating toward the source (incorrect). A certain color emerges at 15o in the first-order spectrum. At what angle would this same color emerge in the second order if the same source and grating are used? Don't forget your two random and two systematic error sources. Back to the Electricity and Magnetism Manual

LED lamp

LED lights can be easily controlled using light intensity regulation technology that allowing users to adjust lighting levels as needed. This provides greater flexibility in creating the desired atmosphere in the room.

LEDStrip lights

One of the main advantages of LED lights is their efficiency in using energy. LED lights can produce light equivalent to conventional incandescent lights with much lower energy consumption. This makes them an eco-friendly and cost-effective option in the long run.

LEDCeiling lights

LED (Light Emitting Diode) lights are one of the modern lighting technologies that are increasingly popular in various applications from household lighting to road lighting. The different is conventional lamps uses filaments while LED lights uses semiconductor diodes to produce light. The advantages offered by LED lights make them a top choice for many people in choosing a lighting system.

Thus, the colors present in the light from the source incident on the grating would emerge each at a different angle since each has a different wavelength . Furthermore, a complete spectrum would be observed for n = 1 and another complete spectrum for n = 2, etc., but at larger angles. Also, the triangle formed by rays to the left of 0o is identical to the triangle formed by rays to the right of 0o but the angles R and L (Right and Left) would be the same only if the grating is perpendicular to the incident beam. This perpendicularity is inconvenient to achieve so, in practice, R and L are both measured and their average is used as in the grating equation. PROCEDURE Calibrating the Spectrometer Read and follow the procedures for calibrating the spectroscope found in the previous experiment. The calibration can be performed with the grating in place on the table. Measuring CAUTION: The diffraction grating is a photographic reproduction and should NOT be touched. The deeper recess in the holder is intended to protect it from damage. Therefore, the glass is on the shallow side of the holder and the grating is on the deep side. Place the grating on the center of the table with its scratches running vertically, and with the base material (glass) facing the light source. In this way, one can study diffraction without the complication of refraction (recall from the previous lab how light behaves when traveling through glass at other than normal incidence). Fix the grating in place using masking tape. Rotate the table to make the grating perpendicular to the incident beam by eye. This is not critical since the average of R and L accommodates a minor misalignment. Affirm maximum brightness for the straight through beam by adjusting the source-slit alignment. At this step, the slit should be narrow, perhaps a few times wider than the hairline. Search for the spectrum by moving the telescope to one side or the other. This spectrum should look much like that observed with the prism except that the order of the colors as you move away from zero degrees is reversed. Search for the second- and third-order spectra. Do not measure the higher-order angles, but record the order of colors away from zero degrees. For each of the seven colors in the mercury spectrum, measure the angles R and L to the nearest tenth of a degree by placing the hairline on the stationary side of the slit. Analysis Average the right and left angles for each color. Use the grating equation with d=(1/6000) cm to find the wavelength for each color. Remember that 108 angstrom = 1 cm. Calculate the percent deviation for each wavelength using % deviation = (data-theory)/theory x 100% where "theory" is the tabulated wavelength from the last experiment. Do not ignore the sign; it contains information. A positive % deviation means that the value is above the theory; a negative % deviation means that the value is below the theory. Do you notice any systematic problems in your seven % deviations? Use the grating equation with the tabulated values of from last time and your measured values of to calculate seven different values of N, the grating constant (N=1/d). Average the seven values of N. For the error on N, use the standard deviation on the mean (SDOM). Compare your answer to the accepted value of 6000 lines/cm. Does your value of N agree with the manufacturer's value within the error range? See Taylor page 5 if you are confused. What could be causing any discrepancy? Why is it necessary that the base side of the grating face toward the light source? Draw a ray diagram for the two cases: a) base toward the source (correct) and b) grating toward the source (incorrect). A certain color emerges at 15o in the first-order spectrum. At what angle would this same color emerge in the second order if the same source and grating are used? Don't forget your two random and two systematic error sources. Back to the Electricity and Magnetism Manual

This type of LED has a high light intensity and is usually used in applications that require strong lighting such as floodlights, street lights, or emergency lighting. High Intensity LEDs provide bright and uniform lighting.

led灯

Unlike incandescent and fluorescent lights that contain mercury, LED lights do not contain this harmful substance. This makes them more environmentally friendly and safe to dispose of after their lifespan is over.

Also, the triangle formed by rays to the left of 0o is identical to the triangle formed by rays to the right of 0o but the angles R and L (Right and Left) would be the same only if the grating is perpendicular to the incident beam. This perpendicularity is inconvenient to achieve so, in practice, R and L are both measured and their average is used as in the grating equation. PROCEDURE Calibrating the Spectrometer Read and follow the procedures for calibrating the spectroscope found in the previous experiment. The calibration can be performed with the grating in place on the table. Measuring CAUTION: The diffraction grating is a photographic reproduction and should NOT be touched. The deeper recess in the holder is intended to protect it from damage. Therefore, the glass is on the shallow side of the holder and the grating is on the deep side. Place the grating on the center of the table with its scratches running vertically, and with the base material (glass) facing the light source. In this way, one can study diffraction without the complication of refraction (recall from the previous lab how light behaves when traveling through glass at other than normal incidence). Fix the grating in place using masking tape. Rotate the table to make the grating perpendicular to the incident beam by eye. This is not critical since the average of R and L accommodates a minor misalignment. Affirm maximum brightness for the straight through beam by adjusting the source-slit alignment. At this step, the slit should be narrow, perhaps a few times wider than the hairline. Search for the spectrum by moving the telescope to one side or the other. This spectrum should look much like that observed with the prism except that the order of the colors as you move away from zero degrees is reversed. Search for the second- and third-order spectra. Do not measure the higher-order angles, but record the order of colors away from zero degrees. For each of the seven colors in the mercury spectrum, measure the angles R and L to the nearest tenth of a degree by placing the hairline on the stationary side of the slit. Analysis Average the right and left angles for each color. Use the grating equation with d=(1/6000) cm to find the wavelength for each color. Remember that 108 angstrom = 1 cm. Calculate the percent deviation for each wavelength using % deviation = (data-theory)/theory x 100% where "theory" is the tabulated wavelength from the last experiment. Do not ignore the sign; it contains information. A positive % deviation means that the value is above the theory; a negative % deviation means that the value is below the theory. Do you notice any systematic problems in your seven % deviations? Use the grating equation with the tabulated values of from last time and your measured values of to calculate seven different values of N, the grating constant (N=1/d). Average the seven values of N. For the error on N, use the standard deviation on the mean (SDOM). Compare your answer to the accepted value of 6000 lines/cm. Does your value of N agree with the manufacturer's value within the error range? See Taylor page 5 if you are confused. What could be causing any discrepancy? Why is it necessary that the base side of the grating face toward the light source? Draw a ray diagram for the two cases: a) base toward the source (correct) and b) grating toward the source (incorrect). A certain color emerges at 15o in the first-order spectrum. At what angle would this same color emerge in the second order if the same source and grating are used? Don't forget your two random and two systematic error sources. Back to the Electricity and Magnetism Manual

light emitting diode中文

LED lights switch on instantly once switched on without the need for warm-up time like incandescent lights. In addition, LED lights do not emit heat like incandescent lights. It makes them safe to use around heat-sensitive objects, and reducing the cooling load on the room.

Chip On Board LED is a type of LED where multiple small LED chips are mounted directly on a substrate together, usually with a layer of phosphor to produce a brighter and more even light. COB LEDs are often used in floodlights or streetlights that require high light intensity and equal intensity of light distribution.

With these advantages, LED lights have transformed the modern lighting landscape and become a very popular choice across a wide range of applications. As innovations in LED technology progress expected that advantages will continue to grow and bring further benefits to the environment and users.

light-emitting diode

LED lights have a much longer lifespan than conventional lights. An LED lamp can typically last up to 25,000 hours or more compared to incandescent lights that only last about 1,000 hours. This reduces the frequency of lamp replacement and maintenance costs.

Bi color LEDs have the ability to emit two different colours of light from a single LED chip. Bi color LEDs can produce two different colors alternately or simultaneously with proper current control. This type is often used in indicator or signal applications.

Because this type of LED is small and compact, it is often used in electronic devices that require lighting in a limited space such as in mobile phone devices, remote controls, or other electronic devices.

Flashing LEDs have the ability to flash periodically. This type of LED light is often used in signalling applications, warning signs, or security devices to attract attention in a visually striking way.

Super Flux LED also known as Piranha LED is a type of LED specifically designed to provide brighter light with a wider angle of illumination. This type is often used in decorative applications, vehicle lighting, or lighting for large areas.

LED (Light Emitting Diode) lights are a type of modern lighting that uses semiconductor diodes to produce light. Electroluminescence effect is the semiconductor diodes in LED lights emit light when an electric current passes through the semiconductor material inside. Conventional lights use a filament to produce light meanwhile LED lights do not require filament heating and it makes more energy efficient.