Science Part 1
science maharashtra board 10th
- Distinguish between: a. Farsightedness and Nearsightedness Farsightedness (hypermetropia) Nearsightedness (Myopia) In hypermetropia, person clearly sees all the far away objects, but is unable to see... 1
- Explain the working of an astronomical telescope using refraction of light. The astronomical telescope consists of two lenses: objective and eyepiece. Objective has larger focal length and diameter to accommodate max... 1
- We can not clearly see an object kept at a distance less than 25 cm from the eye. We cannot clearly see an object kept at a distance less than 25 cm from the eye. This is because when we try to see a nearby object, the eye... 1
- One can sense colours only in bright light. The retina in the eye is made of many light sensitive cells. The rod-shaped cells respond to the intensity of light while the cone-shaped ce... 1
- Simple microscope is used for watch repairs. When an object is placed within the focal length of a magnifying glass or simple microscope (convex lens), its larger and erect image is obt... 1
- At which position will you keep an object in front of a convex lens so as to get a real image of the same size as the object ? Draw a figure. When an object is placed at the centre of curvature 2F₁ of a convex lens, we will get a real image 2F₂ of the same size as the object. 1
- Draw a figure explaining various terms related to a lens Various Terms related with Lenses: 1) Optical centre : The point inside a lens on the principal axis, through which light rays pass without... 1
- Q1} Match the columns in the following table and explain them Column 1 Column 2 Column 3 Farsightedness Faraway object can be seen clearly Convex lens Presbyopia Problem of old age Bifocal lens Nearsigh... 2
- If the absolute refractive indices of glass and water are 3/2 and 4/3 respectively, what is the refractive index of glass with respect to water? 9/8 is Refractive index of glass w.r.t. water 1
- (i). If the speed of light in a medium is 1.5 × 108 m/s, what is the absolute refractive index of the medium? 2 is the absolute refractive index of the medium 1
- C. If the refractive index of glass with respect to air is 3/2, what is the refractive index of air with respect to glass? (i). 1/2 (ii). 3 (iii). 1/3 (iv). 2/3 The correct answer is option (iv). Refractive index of air with respect to glass is 2/3. 1
- B. We can see the Sun even when it is little below the horizon because of i. Reflection of light ii. Refraction of light Correct option is (ii) We can see the Sun even when it is little below the horizon because of refraction of light. 1
- A. What is the reason for the twinkling of stars? i . Explosions occurring in stars from time to time ii. Absorption of light in the earth’s atmosphere The correct answer is option (iv). The reason for the twinkling of stars is changing refractive index of the atmospheric gases. 1
- (ii) A rainbow is the combined effect of the refraction, dispersion, and total internal reflection of light. The rainbow formation in the sky is the combined effect of the refraction, dispersion, and total internal reflection of light. (1) The sunli... 1
- (i) If the angle of incidence and angle of emergence of a light ray falling on a glass slab are i and e respectively, prove that, i = e. In the fig SR || PQ and OM is the reflected ray Hence r₁=r₂ Let μ be the refractive index of the glass slab. Then, according to Snell's law,... 1
- Fill in the blanks and Explain the completed sentences. (i) . Refractive index depends on the ............. of light. (i) Refractive index depends on the wavelengthof light. (ii) The change in directionof light rays while going from one medium to another is... 1
- 4.A calorimeter has mass 100 g and specific heat 0.1 kcal/ kg °C. It contains 250 gm of liquid at 30°C having specific heat of 0.4 kcal/kg °C. Answer: about 20.8 °C Convert specific heats: 0.1 kcal/kg °C = 0.1 cal/g °C and 0.4 kcal/kg °C = 0.4 cal/g °C. Take the latent heat of melti... 1
- A thermally insulated pot has 150 g ice at temperature 0°C. How much steam of 100°C has to be mixed to it, so that water of temperature 50°C will be obtained? Answer: about 33 g of steam Let the mass of steam be m g. Heat gained by ice (melts at 0 °C, then warms to 50 °C): 150×80 + 150×1×50 = 12000... 1
- Liquid ammonia is used in ice factory for making ice from water. If water at 20°C is to be converted into 2 kg ice at 0°C, Answer: about 586.5 g of ammonia Heat to be removed from the water (mass 2 kg = 2000 g, specific heat 1 cal/g °C, latent heat of fusion of i... 1
- Equal heat is given to two objects A and B of mass 1 g. Temperature of A increases by 3°C and B by 5°C. Which object has more specific heat? And by what factor? Correct answer is 5/3 https://youtu.be/vENdt48i2W4 2
- 8. Read the following paragraph and answer the questions. i. Heat is transferred from where to where? Ans: Heat is transferred from the object at higher temperature to the object at lower temperatur... 1
- d. On what basis and how will you determine whether air is saturated with vapour or not? On the basis of amount of water vapours present in the air, it can be either saturated or unsaturated. If the amount of water vapours exceed... 1
- c. Explain the role of latent heat in the change of state of a substances? According to the kinetic model, the total energy of a molecule is the sum of kinetic energy due to its motion (which depends on temperature)... 1
- b Which principle is used to measure the specific heat capacity of a substance? If a system of two objects is isolated from the environment by keeping it inside a heat resistant box, then no energy can leave the box or e... 1