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# Grade 10 Academic Science – Optics Flip Cards - PowerPoint PPT Presentation

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1. Grade 10 Academic Science – OpticsFlip Cards Question 1 You are using a concave mirror. You have placed a burning candle in front of the mirror. You cannot locate the reflected image anywhere. Where must the candle be located relative to the mirror?

2. Grade 10 Academic Science – OpticsFlip Cards Answer 1 The object must be at the Focus (F). All the light rays from the object reflect from the mirror parallel. The reflected rays do not cross. Thus, there is no image.

3. Grade 10 Academic Science – OpticsFlip Cards Question 2 Light travels in air (c) at 3.00 X 108 m/s. The speed of light in water (v) is 2.26 X 108 m/s. As light travels from air to water, the light will be refracted. What is the Index of Refraction (n) in this case? Recall n = c/v

4. Grade 10 Academic Science – OpticsFlip Cards Answer 2 n = c / v n = 3.00 X 108 / 2.26 X 108 n = 1.33 The Index of Refraction is 1.33 meaning the speed of light in air is 1.33X faster than the speed of light in water.

5. Grade 10 Academic Science – OpticsFlip Cards Question 3 In Question 2, we learned light refracted as it moved from air to water. In general terms, which way will the light refract as it moves into water?

6. Grade 10 Academic Science – OpticsFlip Cards Answer 3 Light will refract TOWARD the NORMAL. The Normal is an imaginary line that is perpendicular (90O) to the refracting surface. As light enters water, light speed slows and the light ray moves toward the Normal

7. Grade 10 Academic Science – OpticsFlip Cards Question 4 Match the following sources of light with its product

8. Grade 10 Academic Science – OpticsFlip Cards Answer 4 1D – Incandescence is electricity passing through a thin filament. The filament produces heat and light. This is energy inefficient because it produces mostly heat 2C – Energy Discharges are used in neon lights. Electricity is passed through a gas in a tube causing the gas to glow. 3A – Fluorescence is used in energy efficient light bulbs. Most of the energy produced is light. 4B – Chemiluminescence is light as a byproduct of a chemical reaction. Two chemicals mix in a stick to make it glow.

9. Grade 10 Academic Science – OpticsFlip Cards Question 5 Total Internal Refraction is when the light traveling through a medium does NOT exit the medium. All the light is reflected back into the medium. In essence light does not “emerge” from the medium. It disappears. What TWO conditions must exist for Total Internal Refraction to occur?

10. Grade 10 Academic Science – OpticsFlip Cards Answer 5 Condition 1 Light must be traveling in a slow medium and moving into a faster medium (e.g., light in water moving to air). Condition 2 The Angle of Incidence from the ray traveling in the slower medium must be greater than the Critical Angle. Recall, the Critical Angle is when the Angle of Incidence produces an Angle of Refraction of 90O. Since the Normal is a line perpendicular to the refracting surface, the light travels along the refracting surface. If Angle of Incidence > Critical Angle, the Angle of Refraction > 90O. All light is reflected back into the medium.

11. Grade 10 Academic Science – OpticsFlip Cards Question 6 A light-producing object is placed between 2F and F for a converging lens. What type of image is produced? Describe the image using SALT.

12. Grade 10 Academic Science – OpticsFlip Cards Answer 6 The image is -- S (size) = Larger A (attitude) = Inverted L (location) = Beyond the lens T (type) = Real The light rays travel through the lens. A ray passing through the Optical Centre (…centre of the lens) will keep going straight. A ray going through F in front of the lens, goes to the lens and then runs parallel to the Principal Axis beyond the lens. The ray traveling parallel to the Principal Axis, strikes the lens and goes through F on the other side of the lens. The three rays will meet and make a real image as shown

13. Grade 10 Academic Science – OpticsFlip Cards Question 7 You are looking at a butterfly through a leaf. The butterfly outline is visible, but details (e.g., colour, body hairs) cannot be seen clearly. Relative to light, what sort of object is the leaf?

14. Grade 10 Academic Science – OpticsFlip Cards Answer 7 The leaf is translucent. The leaf transmits some incident light, but it also absorbs or reflects some light. Thus, the butterfly cannot be seen clearly. If the leaf had been transparent, the butterfly…with all its colour and body markings…would be seen clearly. If the leaf had been opaque, all the incident light would be absorbed or reflected. The butterfly would not be seen at all.

15. Grade 10 Academic Science – OpticsFlip Cards Question 8 We all like looking at diamonds. Diamonds seem to sparkle light in every direction. The sparkling effect has two causes. The first cause is the many cut faces of the diamond. The faces mean incident light enters the diamond from many different angles. What is the second reason for multiple sparkles?

16. Grade 10 Academic Science – OpticsFlip Cards Answer 8 Diamond has a high Index of Refraction (n = 2.42). This means that light travels 2.42X faster in air than diamond. Inside the diamond, light travels slowly. When it tries to exit the diamond, the light will be moving back into a fast medium. If the Angle of Incidence of the traveling light in the diamond is greater than the Critical Angle, Total Internal Refraction occurs (i.e., all incident light reflects back into the diamond). This continues until the Angle of Incident < Critical Angle. At this point, the light exits. It can exit as one ray of light, or the ray can disperse into all the colours of visible light. Since light enters from many angles, it also exits are varied angles, and thus, a diamond sparkles.

17. Grade 10 Academic Science – OpticsFlip Cards Question 9 You are told (…by me…lol…) that light travels in a straight line. Do you believe it? Provide two pieces of evidence that light travels in a straight line.