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Questions : 1, 2 and 3 (in Hindi)
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In this lesson, we'll discuss on 3 questions and try to make some strategy for doing that type of questions in exams

## Kumar Ketan is teaching live on Unacademy Plus

Kumar Ketan
#Specialisation in Electronics #6 years teaching experience #Physics Faculty in Kota #"magical education" (231k+ subs) #Writer

U
sc st ka cutf kitne par jayega
Kumar Ketan
9 months ago
All courses on my profile are for JEE and NEET
Kumar Ketan
9 months ago
Aur detail me pdhna chahte h aap to Mai apko suggest krna chahunga ki plus subscription jrur lijiye qki wha apko best live classes, PDF notes, test papers etc milege... Aur refrral code use krke aap 10% discuss bhi le skte h... Refers code h - KumarKetan
3rd hogya bt 2nd m force calculate krne m dikkat hui lekin ab ah gyi thnku sir
Kumar Ketan
a year ago
Good, keep practicing
sir plzz upload more lectures i hope this course will inhace my mark
sir please make more of such videos . Questions are really nice .
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sir remaining 130 questions kab upload honge

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2. Que. What is the minimum thickness of a thin film required for constructive interference in the reflected light from it? Given, the refractive index of the film-1.5, wavelength of the light incident on the film- 600 nnm (a) 100 nm (c) 50 nm (b) 300 nm (d) 200 nm

3. Condition for constructive interference is 2 where, n o, 1, 2, 3,.. For minimum thickness, n o 600 10-9 4 4x1.5 2

4. Que. A body of mass 60 kg is dragged with just enough force to start it moving on a rough surface with coefficients of static and kinetic frictions 0.5 and 0.4 respectively. On applying the same force, the acceleration is (a) 0.98 m s-2 (c) 0.54 m s (b) 9.8 m s2 (d) 5.4 m s2

5. When the body is in motion, net force acting on the body, (. R mg) or a- - (0.5 - 0.4) x 9.8 0.98 m s4

6. Que. To determine surtace tension of water by experiment, capillary tube method is used. In Prgh relation is used. this method, T = 2 Here, Tsurface tension, p-density of water, gacceleration due to gravity, h rise of water in capillary tube, r- radius of capillary tube. The percentage error in the measurement ofp, r, g and h are 1%, 2%, 1% and 2%, respectively, error in the measurement of surface tension is n%. Find the value of n. (a) 6% (b) 6.1% (c) 0.5% (d) 5.1%

7. T=prgh 2 Percentage error in surface tension is ap Ag ar x100- 100+ 100+ 100 +-- 100

8. 1+2+1+2=6% n=6

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