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Gouri Lahoti
Subject: Science
, asked on 19/2/18
Please answer and give reason for ur answer.
Q.10. A convex lens gives a full image of a distant tree. If half the lens is covered with an opaque object.
then:
(a) Half of the image is not seen
(b) Full image of the same intensity is seen
(c) Full image of decreased intensity is seen
(d) Half image of decreased intensity is seen
Answer
2
Shrish Vaidya
Subject: Science
, asked on 19/2/18
A student has to project a three times magnified image of a candle flame on a wall. Name the type of the lens (converging/ diverging) required for the purpose. If the candle flame is at a distance of 6 m from the wall, find the focal length of the lens.
Answer
2
Shrish Vaidya
Subject: Science
, asked on 19/2/18
Q4. When a concave mirror is placed facing the Sun, the Sun's rays converge to a point 10 cm from the mirror. Now, if you place a 2 cm long candles flame 20 cm away on the principal axis of the mirror, where would you place a screen to obtain the image of the candle? What would the size of the image? Draw a ray diagram to justify your answer.
Q5. If you find coliform bacteria in a sample of water collected from a river, what would you conclude ? Give reason for such kind of water pollution.
Answer
2
Raghav Singh
Subject: Science
, asked on 18/2/18
Between which two points of a concave mirror should an object be placed to obtain a magnification of –3?
Answer
3
Raghav Singh
Subject: Science
, asked on 18/2/18
Q. How many images are formed for a point source kept in between two plane mirrors
M
1
a
n
d
M
2
at right angles to each other? Explain the answer.
Answer
1
Sanitya Srivastava
Subject: Science
, asked on 18/2/18
What is the difference between refractive index and absolute refractive index?
Answer
1
Mahek Harwani
Subject: Science
, asked on 18/2/18
The refractive indices of four media A, B, C and D are given in the following table
Medium
A
B
C
D
Refractive index
1.33
1.50
1.52
2.40
If light travels from one medium to another, in which case the change in speed will be (I) minimum (ii) maximum?
Answer
3
Parul Garg
Subject: Science
, asked on 18/2/18
One half a convex lens of focal length 10 cm is covered with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens? Draw a ray diagram to justify your answer.
A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 15 cm. Find the nature, position and size of the image.
Answer
1
Mahek Harwani
Subject: Science
, asked on 18/2/18
a ray of light travelling in air strikes the glass surface at an angle of incidence of 60 degree the corresponding angle of refraction be 45 degree. find the angle of refraction in glass if refractive index of glass is 3/2.. no links plzz
Answer
1
Mahek Harwani
Subject: Science
, asked on 18/2/18
the angle of incidence in air for a ray of light is 45 degree . if the ray travels through water of refractive index 4/3. find the angle of refraction.
Answer
1
Champ Jee
Subject: Science
, asked on 17/2/18
Explain why sheet of plane paper and mirror both reflect light we wee see our reflection only in mirror.
Pls no links and explanation best. Thanks.
Answer
1
Raghav Singh
Subject: Science
, asked on 17/2/18
Q. When some coloured syrup is added to water in a glass, the glass appears to be coloured from top, but when seen from sides its colour intensity is at the bottom. Is it refraction of light?
Answer
3
Shivam
Subject: Science
, asked on 17/2/18
Pls ans this ques fast SCIENCE
Q.3. Rohit focused the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle , screen and lens as under :
Position of candle = 26.0 cm
Position of convex lens = 50.0 cm
Position of screen = 74.0 cm
i) What is the focal length of the convex lens?
ii) Where will the image be formed if he shifts the candle towards the lens at a position of 38 cm?
iii) Draw a ray diagram to show the formation of the image in case (ii) as said above?
Answer
2
Raghav Singh
Subject: Science
, asked on 17/2/18
Please solve my query in the picture. I want to know the reason why we don't take 50/3/-25 as 50 * -25/3 in physics . Please.
Answer
2
Raghav Singh
Subject: Science
, asked on 17/2/18
Please tell me the reason that why i am getting wrong answer in the calculation. In maths 50/3/-25 is 50* -25/3 (as we multiply by the reciprocal) but in physics it is 50/3*1/-25 why? Is calculation in physics different from maths?
Answer
1
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Q.10. A convex lens gives a full image of a distant tree. If half the lens is covered with an opaque object.
then:
(a) Half of the image is not seen
(b) Full image of the same intensity is seen
(c) Full image of decreased intensity is seen
(d) Half image of decreased intensity is seen
Q5. If you find coliform bacteria in a sample of water collected from a river, what would you conclude ? Give reason for such kind of water pollution.
If light travels from one medium to another, in which case the change in speed will be (I) minimum (ii) maximum?
A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 15 cm. Find the nature, position and size of the image.
Pls no links and explanation best. Thanks.
Q.3. Rohit focused the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle , screen and lens as under :
Position of candle = 26.0 cm
Position of convex lens = 50.0 cm
Position of screen = 74.0 cm
i) What is the focal length of the convex lens?
ii) Where will the image be formed if he shifts the candle towards the lens at a position of 38 cm?
iii) Draw a ray diagram to show the formation of the image in case (ii) as said above?