Learning with Amit Kumar Chand: Tutoring Sessions

Answer

Let's say initial velocity is u , now rate of being slow i.e negative aceleration a = 2 m/s2 . And it finally comes to rest so final velocity is v=0 , So, from the relation : v=u - a*t we get 0 = u - 2*10 , then u = 20 m/s

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current coil carrying current behaves as a solenoid. So, no 4 is correct answer.

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Three balls to be drawn with at least one black ball . So, it may be 3 blacks or 2 blacks with another one or 1 black with another 2. Now total black balls are 3 and total number of other balls is 6 . Now the required number will be ( 3C3 + 3C2 * 6C1 + 3C1* 6C2 ) = ( 1 + 3*6 + 3*15) = 64

Answer

The voltage and current depend on number of photons coming to the photoelectric cell. Now number of photon will vary as 1/r^2 . So voltage will vary like this and we can write V1/V2 = r2^2/r1^2 then V2 = r1^2 * V1/ r2^2 or V2 = 0.2^2 * 0.6/ 0.6^2 or V2= 0.6/9 = 0.067 Volt Similary current will change I1/I2 = V1/ V2 then I2= V2* I1/V1 = 0.067*18/0.6 = 2 mA

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She was north facing ---  left tern west facing --- again left tern south facing. Two left tern make her opposite facing of initial which was north. So now she at point Z is south facing.

 

Answer

Lets say average of 15 students is x . So total marks by 15 students is 15*x . If the 16th student score 112 marks then total marks becomes 15*x+112 . Now the average of 16 students is ( 15*x + 112) / 16 . Again, this average is ( x+2) as mentioned in question. So, ( 15*x+112)/ 16 = x+2 => 16*x + 32 = 15*x + 112 => 16*x - 15*x = 112 - 32 => x= 80.

So, average of 15 students is 80 and clearly average of 16 students is (80+2) = 82.

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Refractive index of diamond is 2.41 with respect to air. Refractive index of diamond with respect to water is simply 2.41 / 1.33 = 1.81

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From the Snell's law,

n1 * sin ( i ) = n2 * sin ( r ) , now here n1 is air so n1=1 and n2= 1.5  and incident angle i = 30

so, sin (30) = 1.5 * sin ( r ) => 0.5 = 1.5 * sin ( r)  => sin (r) = 1/3 => r = sin -1 ( 1/3 ) = 19.47 degree

Answer

F=B*I*L*sin( A )  , here B is the magnetic filed , I = current , L = length of the wire and  A = angle between magnetic field and current flow

now for this case A= 90 degree as East - West directions are perpendicular to earth magnetic filed

L = 1 as the required force is of unit length

so formula becomes, F= B*I = 0.0001 * 10 = 0.001 N

Answer

LCM of 30 and 42 and the multiples of the LCM are exactly divisible by 30 and 42.

Now LCM is 210

now 210/84 = 2.5 

we need an integer so 2.5*2 = 5 

so smallest no is 5