Doubtly
@Doubtly · Joined Feb 2021
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- Draw the energy band diagram when intrinsic semiconductor (Ge) is doped with impurity atoms of Antimony (Sb). Answer :diagram: 2
- A particle of mass m with an initial velocity collides perfectly elastically with a mass 3 m at rest. It moves with a velocity The correct answer is option d) v=uover sqrt 2 Explaination :: mui+0=mvj+3mv' v'=uover3i-vover3j 1over2mu²=1over2mv²+1over2(3m)Big(big(uover... 1
- A particle executes simple harmonic motion with an amplitude of 5 cm. When the particle is at 4 cm from the mean position, the magnitude of its velocity The correct option is answer a) 8π/3 EXplaination :: v= w√(A²-x²) --speed Acceleeation a= -ω ²x As |v|=|a| ω =3over4⇒T = 2πover ω = 8πover3 1
- The mass of a spaceship is 1000 kg. It is to be launched from the earth’s surface out into free space. The correct answer is option (a) 6.4 x 10^(10 )Joules Explaination :: The energy required is given by = GMmover R = gR² × mover R (∵ g = GMo... 1
- If the distance between the earth and the sun were half its present value, the number of days in a year would have been The correct answer is 129 days option b Explaination : BY keplers third law T² ∝ R³ therefore ( T₂over T₁)²=( R₂over R₁)³ T_(1 )= 365 days ,... 1
- If the current flowing in a coil is reduced to half of its original value, The Correct option is D) E₂ = 1over4 E_(1 ) Explaination Current is become half of the given value. E=1over2Li² i.e. E₂over E₁=(i₂over i₁)²=... 1
- Evaluate int {root x^2 + a^2} dx solve this question This can be best answer possible https://youtu.be/BmCM98ymuiY This video belongs to ganit yogi if they want we can remove it from here . 2
- Find the value of A and B if int(sinx/sin(x-alpha))dx= Answer: (b) (A, B) = (cosα, sinα) Write x = (x-α) + α , so sin x = sin(x-α)cosα + cos(x-α)sinα. Dividing by sin(x-α) : sin x/sin(x-α) = cosα... 1
- If f(x) = ∫t(sinx - sint)dt for t ∈ [0, x] then (A) f'''(x) + f''(x) Answer: (C) f'''(x) + f'(x) = cos x - 2xsin x Write f(x) = sin x∫₀^x t dt - ∫₀^x tsin t dt = dfracx²2sin x - (sin x - xcos x) . Differentiat... 1
- evaluate int x-1/(x+1)^3 e^x dx {integration question } The correct answer is e^xover (x+1)²+c Explaination: 1
- l,m,n are the pth and rth term of G.P all positive then Correct option is 4) 0 Let x and y are first term and common ratio of GP respectively. first and second row are identical =0 1
- find the value of α for which A2 = B, is The correct answer is option d) no real value Explanation:: 1
- A ^−1 = 1/6(A^ 2 +cA+dI) where c, d ∈ R, then pair of values (c, d) are _________ Correct answer is -6,11 Explanation::: 1
- A time-dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest, the work done by the force during the first 1 sec. will be : The correct option is c) 4.5 J F= 6t, m = 1Kg, u =0 Now, F=ma =m(dv/dt)=1x(dv/dt) dv/dt = 6t ∫ ^v₀dv =∫¹₀6tdt v= 3(1²– 0) = 3m/s From work-e... 1
- At time t = 0s particle starts moving along the x-axis. If its kinetic energy increases uniformly with time ‘t’, The correct option is d) 1/√(t) Linear dependency with initial Kinetic Energy as zero is given as KE = kt, where k is the proportionality co... 1
- Two masses of 1 g and 4g are moving with equal kinetic energy. The ratio of the magnitudes of their momenta is The correct option is c)1:2 p=√(2Em) Where p denotes momentum, E denotes kinetic energy and mdenotes mass. p₁over p₂=√(m₁over m₂) p₁over p₂... 1
- A body of mass m=10−2 kg is moving in a medium and experiences a frictional force F=−kv2. Its initial speed is v0= 10 ms−1. (c) 10⁻⁴ kg m−1 is the correct answer Mass m = 10² Kg Initial velocity v₀= 10 ms⁻¹ Time t = 10 s Frictional Force F=− kv² 1/2 mv_f^(2 )= ⅛ m... 1
- Consider a car moving on a straight road with a speed of 100 m/s. The distance at which a car can be stopped is : (μk = 0.5) b) is the correct option i.e. 1000 When the car is stopped by friction then its retarding force is ma = μR ma = μmg a= μg Consider the equat... 1