OMI lab 2 Exam Study With Complete Questions And Answers.

Polarisation-What happens to the colour of the torch light in milky water? - correct answer Turns yellow/orange Particles inside the milky water cause light scattering Shorter wavelengths (blue) leave the light source first and scatter into the milk Longer wavelengths remain in the light source and pass through Polarisation-Why does torch light appear more yellow as we add more milk? - correct answer More milk = more light scatter Short wavelengths (blue) scatters more into milk, causing the torch light to appear more yellow (as it has a longer wavelength) and the milk to appear more blue Polarisation-Why would using a red light source not work? - correct answer Red only contains long wavelength light Long wavelength light is more difficult to scatter and lack the full range of wavelengths (as with white light) There are no short wavelength (blue) light to scatter and make milk blue Polarisation problems-> light source doesn't turn yellow but milk turns blue - correct answer source producing diffuse light Angle the light source downwards towards the table or change the light source 2. not added enough milk Polarisation problems- light source disappear when milk is added - correct answer 1. too much milk is added 2. light source is too low Camera obscura-How does the pinhole produce an upside down image? - correct answer Light travels in a straight line through the pinhole However a pinhole is very small, therefore: From the tip of the object appears at the bottom of the image From the bottom of the object appears at the top of the image Camera Obscura-Will the image also be flipped left-right? - correct answer Yes the image will be laterally reversed because light travels in a straight line through the pinhole so light travelling from the right will end up on the left, and light travelling from the left will be on the right of the image. Camera Obscura- What happens to image size and appearance if distance between screen and pinhole increases? - correct answer Image size increases Image appears less bright because light is spread over a larger area Camera Obscura- What happens to image size and appearance if distance between screen and pinhole decreases? - correct answer Image size decreases Image appears brighter because light is spread over a smaller area Camera Obscura- How does increasing the distance between screen and pinhole produce a larger image? - correct answer If object is still, angle of rays on the other side of the pinhole remain constant If screen is closer to the pinhole, it can see more of the scene than far away Camera Obscura problems- no image seen(dark) - correct answer 1. pinhole too small 2. object not bright enough Camera Obscura problem- no image seen(bright0 - correct answer 1. pinhole too large 2. screen too opaque/translucent temporarily remove screen tube and you should see diffuse light source. Camera Obscura problems- image not upside down - correct answer 1. pinhole too large ng through the camera the wrong way speed of light- How are hotspots formed? - correct answer Microwaves interfere with each other, causing formations of hotspots in locations of constructive interference Speed of Light-How do microwaves heat food? - correct answer The micro waves are absorbed by fats, sugars, proteins and water causing them to heat up. Speed of light-What is the purpose of a microwave turntable? - correct answer The turntable allows the interference produced by the microwave to be evenly spread around the food as it rotates through the hotspots Speed of light-Why is the distance between hotspots equivalent to half the wavelength? - correct answer As amplitude increases away from the midpoint, energy also increases This means both the peak and trough of the microwave profile will produce the highest amount of intensity (heat) Microwave produce two hotspots - one at the peak and one at the trough. The distance between them is half a wavelength Speed of light-Explain why we need to take the turntable out of the microwave for the hotspots to form - correct answer The turntable causes the hotspots to move We need to make sure the hotspots don't move, so the turntable must be removed. Speed of light problems- Chocolate melts - correct answer left in microwave too long Speed of light problems- hot spots very large - correct answer left in microwave too long chocolate was moved during the process speed of light problems- distance between hotspots is too small/large - correct answer chocolate was moved during process distance was not measured from equivalent points(left to left for maximum accuracy) Prism-How can you tell which angle is the apical angle of the prism? - correct answer The apical angle is always between the first and second face of the prism where the light is entering Prism-What points do we need to consider when lining up the protractor to measure the angle of refraction? - correct answer Ensure the centre of the protractor is lined up with the position where the light is leaving the prism Use the middle of the rainbow (yellow) to judge the angle of refraction Subtract from 90° (because angle of refraction needs to be angle between normal - which is at 90° - and light ray) Diffraction-How does the image differ when using gratings with fewer lines per mm compared with a grating with higher lines per mm? - correct answer Has more maxima, and they are closer together.